Ukraine on Tuesday urged the world to provide more help to overcome the effects of the Chernobyl nuclear disaster, saying Kiev had been left alone to fight the fallout for too long.
Prime Minister Mykola Azarov said that Ukraine's total economic losses from the disaster amounted to 180 billion dollars and said that in some years its spending on overcoming Chernobyl amounted to 10 percent of the state budget.
"Despite difficult economic circumstances, Ukraine for the last 20 years has been financing on its own the expenses on overcoming the disaster," Azarov said in a statement.
"We are sure that the solidarity of nations and states, the humanism of modern civilisation will not leave Ukraine without help from outside," he said. "We thank those who give it and, in advance, thank those who will offer it."
The disaster 25 years ago on 26 April 1986 took place while Ukraine was still a Soviet republic. Its post-independence leaders have long complained of the scale of the problem they inherited after the collapse of the USSR.
Azarov said that in Ukraine alone, 2.2 million people have status as victims of Chernobyl, 255,000 of whom are officially recognised as "liquidators" who were involved in the clean-up effort.
"Chernobyl left behind social and economic problems which will not go away for years," he said.
As well as the massive payments for medical assistance, relocation and compensation for victims, Ukraine also needs funds to build a new shelter over the destroyed reactor which is still covered by a Soviet-era sarcophagus.
The European Bank for Reconstruction and Development (EBRD), which is running the project, has yet to win full funding. A conference last week secured 550 million euros ($785 million) in new pledges, short of the 740 million euros still needed.
"For too long, unfortunately, Ukraine remained alone in the Chernobyl disaster. Today we are not alone," President Viktor Yanukovych said in his statement to mark the anniversary.
The world on Tuesday marked a quarter century since the worst nuclear accident in history at Chernobyl in Ukraine, haunted by fears over the safety of atomic energy after the Japan earthquake.
Russian President Dmitry Medvedev is making a landmark visit to Chernobyl later on Tuesday to take part in memorial ceremonies at the stricken plant, joined by his Ukrainian counterpart Viktor Yanukovych.
At a nighttime service led by Russian Orthodox Patriarch Kirill in Kiev, a bell struck at 1:23 am (2223 GMT Monday) -- the moment when the explosion struck -- and tolled 25 times for the years that passed since the disaster.
Inhabitants of the new city of Slavutych, built to safely house workers after the disaster, lit candles beneath a memorial containing pictures of the rescue workers and plant workers who died in the disaster.
"Chernobyl will forever remain a symbol of huge human grief," Medvedev said before visiting Chernobyl, adding that he will propose a plan to boost safety at the world's nuclear power plants at the Group of Eight summit next month.
"Chernobyl has become a challenge of planetary magnitude," Yanukovych added in a statement.
In the early hours of 26 April1986, workers at the Chernobyl atomic power station in the then Soviet republic were carrying out a test on reactor four when operating errors and design flaws sparked successive explosions.
Radioactive debris landed around the reactor, creating an apocalyptic scene in the surrounding area, while material also blew into the neighbouring Soviet republics of Belarus and Russia and further into western Europe.
Two workers were killed by the explosion and 28 other rescuers and staff died of radiation exposure in the next months. Tens of thousands needed to be evacuated and fears remain of the scale of damage to people's health.
Moscow stayed silent on the Chernobyl disaster for three days, with the official news agency TASS only reporting an accident there on April 28, after the Forsmark nuclear plant in Sweden recorded unusually high radiation.
"The world had not known a catastrophe in peaceful times that could compare to what happened in Chernobyl," Kirill said, adding that the fallout from the disaster was comparable to that from the US atomic bomb dropped over Hiroshima multiplied by 500.
In 1986 and 1987, the Soviet government sent more than half a million rescue workers, known as liquidators, to clear up the power station and decontaminate the surrounding area but who now complain of shoddy treatment by authorities.
"Initially, I was treated like a hero," said Russian rescue worker Vladimir Kudriashov, who took part in the rescue effort from September-October 1986 and now suffers from severe heart problems.
"I was given travel and free medicine. But since the law was changed (on the assistance for former liquidators) I have nothing," he complained.
The anniversary has gained an eerily contemporary resonance after the March 11 earthquake and tsunami in Japan which damaged reactors at the Fukushima Daiichi power plant and prompted leaks of radiation.
In Tokyo, Japan's Chief Cabinet Secretary Yukio Edano however insisted that the two cases were "different in nature."
"Unfortunately the amount of radioactive material leaked was about one-tenth (of Chernobyl), but at least we were able to avoid explosions of the reactors," he said.
Despite the notoriety of Chernobyl, controversy has raged for years even between the UN's own agencies over the number of deaths directly caused by the disaster, with estimates ranging from tens of thousands to just dozens.
Some experts have said the worst health legacy of Chernobyl is mental rather than physical, with those affected traumatised by the memory of April 1986, forced relocation and the sense that they are victims of nuclear catastrophe.
In 2005, several UN agencies including the World Health Organisation, said in a report a total of 4,000 people could eventually die as a result of the radiation exposure.
But the UN Scientific Committee on Atomic Radiation (UNSCEAR) says other than the 30 confirmed deaths in the immediate aftermath, only 19 ARS (Acute Radiation Syndrome) survivors had died by 2006 for various reasons.
Other than 6,000 cases of thyroid cancer -- a usually treatable condition -- from contaminated milk there was "no persuasive evidence" of any other effect on the general population from radiation, it said in a report in February.
But environmental campaign group Greenpeace in 2006 accused the UN agencies of grossly underestimating the toll, saying there would be an estimated 93,000 fatal cancer cases caused by Chernobyl.
Chernobyl continued producing energy until well after the collapse of the Soviet Union. Reactor number two shut after a fire in 1991, reactor number one closed in 1997 but reactor number three went on working right up until December 2000.
Short link: