"They are full of goodwill, but they will need to double their numbers and work for months to clean the beach," sighs the head of the clean-up operation, Commander Christian Nedelec.

The French naval officer helps the Lebanese authorities to clear away the after-effects of the oil slick caused by Israeli bombing of a power station in mid-July.

Ramlet al-Beida, or "white sands" in Arabic, is a 1.6 kilometre-long (one-mile) beach, and only one of the many sites among dozens to have been hit by the massive wave of pollution.

The thousands of tonnes of fuel oil have spread to some 30 beaches and coves since the Israeli bombing of storage tanks at the Jiyeh power station, to the south of the Lebanese capital.

Only 400 of the 15,000 tonnes of spilt fuel oil has so far been recovered, according to Lebanon's environment ministry.

"Preventive measures are being taken to isolate the fuel oil in the coves, but the clean-up campaign only started at the end of August," after a ceasefire in the 34-day war between Lebanon's Hezbollah and Israel, says Nedelec.

It was only then that the French volunteers were able to survey the coast from the air, and fly in the necessary clean-up materials.

"(Today) our priority is to train up local teams, because we won't remain here forever," adds the commander, who is one of a nine-member French navy team doing the training.

Jana, 20, of the Lebanese non-governmental organisation Greenline and promoted to supervise the site, is equipped with a whistle and blows it to summon her team of workers.

"The young (local) people who saw us working came to volunteer, but they are all inexperienced and require training," she says.

She complains about the lack of support from the environment ministry, which she says has so far done nothing to recruit new members. "The volunteers don't even know where to go," she adds.

The ministry estimates it will take more than a decade to complete the campaign, provided that 1,000 people take part in it.

With their hands protected by gloves, Cyrielle and Marielle Khayat, sisters aged 19 and 20, perspire heavily under a blazing sun, dragging behind them a garbage sack weighing about 30 kilograms (66 pounds).

"It's hard but essential that the Lebanese clean their coast and not foreigners," says Marielle, a student at the American University of Beirut.

Philippe Mazin, an expert from the French navy, shows them what to do.

"You have to strip the surface and then attack the sand at the edge of the water where the oil has gone down half a metre. It's all got to be done by hand. You can't use machines to clean up sand," he explains.

The experts are wary that sands of different density do not mix, which can be a possible threat to the balance that allows beaches to resist erosion.

Half a kilometre (500 yards) away, clean-up crews were pumping out the black oil from a small cove used by fishermen. The cliff hugging the waterline has absorbed the oil, turning the white limestone rock into black.

"At this rate, they won't finish for months and the high waves of winter that rise several metres will pollute the rest of the cliff," warns Abed Mahfouz, a fisherman.