Updated

French fishermen angry over soaring world oil prices disrupted shipping in the English Channel and blocked deliveries Friday at two refineries of oil giant Total SA, stepping up protests that have hobbled ports around France.

Many fishermen have rejected a government offer earlier this week to speed up promised aid to help them cope with high fuel costs and are taking new actions to call attention to their plight.

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Some 25 trawlers severely slowed traffic in the Dover Strait, a crucial and busy shipping passage between the Atlantic Ocean and the North Sea, according to the maritime administration of the Manche and Nord regions on the northern French coast. The trawlers formed a line near the Boulogne-sur-Mer port in what they called "Operation Snail."

The administration boosted surveillance of the strait, including by helicopter, and alerted counterparts in Britain and Belgium to prevent collisions.

Other protesters blocked delivery trucks from entering or leaving Total oil refineries at Dunkirk and Gonfreville on the English Channel, company spokeswoman Elisabeth de Reals said. She said the refineries were continuing to work as usual but could not take or make deliveries.

The protesters have staged scattered blockages at ports and oil terminals along France's coasts since last week, part of a wave of French frustration at economic difficulties and President Nicolas Sarkozy's reform plans.

Nearly 300,000 people marched nationwide Thursday and public servants went on strike over a plan to extend the retirement age.

On Friday, some 30 fishermen in the Bouches-du-Rhone region on France's Mediterranean coast took over a tollbooth and were allowing drivers through for free, said Frederic Mateo, head of the regional trawler operators' union.

They were handing out fliers to drivers to explain their protest. Mateo said the fishermen want even faster action by the government to cap diesel prices.

On Wednesday, the government tried to assuage the fishermen with immediate aid and faster access to a $488 million package already promised.

Protesters have clashed with police and ransacked supermarkets selling imported fish. Some are seeking to expand their action Europe-wide.

Meanwhile, oil terminal blockades earlier this week spurred panic gasoline-buying among car owners.

French doctors who perform house calls in their own vehicles also spoke out Friday about high fuel prices, demanding that the state health care system take "urgent measures" to help defray the costs.

Michel Chassang of the National Center of Health Professions called it "financially intolerable" for such state-paid doctors, and threatened protests if their needs are not met.