Italian authorites said Saturday they were monitoring a two-kilometre- (1.25 mile-) long oil slick off the country's Riviera coast but said the risk of a new spill into the Mediterranean was under control.
The slick, which was 500 metres wide, was moving slowly westwards from waters off Genoa, raising fears it could end up polluting holiday beaches on a stretch of coastline that straddles the border with France just as the tourist season begins.
The oil is believed to have come from a pipeline leak at a refinery located at Bussala, an outlying suburb of Genoa, on April 17.
The refinery's owner, Iplom, insisted that the leak into the Polcevera river was contained within hours. One of the barriers erected on the river gave way on Saturday morning after heavy overnight rain, raising fears tonnes more crude could reach the sea.
After declaring a local state of emergency, Genoa's port authority and the government said that back-up floating barriers in the mouth of the river had done their job.
"The situation is delicate but under control," said Graziano Delrio, the minister for transport and infrastructure. Further heavy rain was forecast for Saturday evening.
Genoa mayor Marco Doria said the large slick and several smaller ones spotted by fishermen and coastguards had presumably been caused by last Sunday's incident.
The leak sent large quantities of oil into the Polcevera but the company claimed to have contained it within hours and to have since made good progress in extracting it.
"From an environmental point of view I am calm. There was no new leak into the sea," said Gianfranco Benedettil, Iplom's local safety officer. "There is not much stuff left in the Polcevera, most of it has been extracted by gully suckers," he told the AGI newswire.
The refinery where the leak came from is due to suspend its operations on Monday for economic reasons.
Genova is located in the middle of the Italian stretch of the Riviera, close to the famous resort of Portofino and several protected areas of outstanding natural beauty, including the Cinque Terre region.
The maritime environment is also highly prized with the coastal waters providing valuable breeding grounds for sealife as well as supporting a dayboat fishing fleet which serves the local restaurant trade.