A series of bombs in Gaza Friday targeting the Fatah movement of Palestinian president Mahmud Abbas triggered a bitter new spat with rivals Hamas in a blow to reconciliation efforts.
At least 10 blasts hit the homes and cars of several Fatah officials, triggering a furious response from the party which placed the blame squarely on Hamas, the de facto rulers in Gaza.
There were no immediate reports of casualties from the early morning bombs.
Palestinian prime minister Rami Hamdallah, who had been due to visit Gaza on Saturday with new EU foreign affairs chief Federica Mogherini, promptly cancelled his trip.
One of the explosions targeted a stage in western Gaza City set up for a ceremony marking the 10th anniversary on Tuesday of the death of veteran Palestinian leader Yasser Arafat, who founded Fatah.
This year is the first time in years a public commemoration of Arafat's death is to be held in Gaza, which has been ruled by Hamas since 2007 when the movement ousted forces loyal to Fatah, sparking a bitter and sometimes bloody feud.
For seven years, Gaza and the West Bank were ruled by separate administrations until the two factions inked a deal in April which led to the formation of a national unity government that took office in June.
Based in the West Bank city of Ramallah, the unity government -- which is formed of technocrats -- has yet to fully take up its functions in Gaza where Hamas has remained the de facto authority.
"Fatah condemns and deplores the explosions targeting the homes and property of its leaders and the stage," said a statement from the party.
"Bombing the stage is evidence that those behind the attacks are looking to derail the national unity agreement and the festival," it said, demanding that the unity government investigate who was behind the attacks.
Hamas also condemned the violence, describing it as a "heinous crime aimed at damaging (Gaza's) internal stability."
"Hamas strongly condemns this criminal incident in which some Fatah houses were targeted. We call on the security forces to investigate and to bring the involved to justice," spokesman Sami Abu Zuhri said in a statement.
Several top Fatah officials lashed out, placing full responsibility for the attacks on Hamas.
"The Fatah central committee condemns the crimes which took place this morning against its leaders and lays the responsibility for these crimes upon Hamas," senior Fatah official Nasser al-Qidwa told reporters in Ramallah.
Azzam al-Ahmed, a top Fatah official who is responsible for all issues affecting the reconciliation efforts, said the fact that the Islamist movement had condemned the attacks "does not absolve Hamas from bearing full responsibility."
According to Fayez Abu Eita, Fatah's Gaza-based spokesman, a threatening letter signed by "the Islamic State movement" was found outside each house that was targeted, accusing the owners of being "traitors and collaborators."
But he dismissed the letters as "ridiculous" saying it was likely that the explosions were linked to the planned Arafat memorial, which he said would go ahead.
"We are not accusing anyone but we hold the Hamas security forces responsible as they control Gaza," he told AFP.
Ahmed also agreed the attacks were likely linked to the anniversary, saying there had been warning signs.
"The most significant (indication) was that of a group of Hamas military officials said they were going to torpedo planned commemorations of the death of President Yasser Arafat," he said.
Arafat died in a French military hospital on November 11, 2004 in mysterious circumstances with many Palestinians believing he was poisoned by Israel.