Greek authorities struggled to restore fuel supplies yesterday after failing to break a six-day trucker strike that has disrupted travel at the peak of the busy tourism season.

Military trucks and petrol company vehicles were employed to alleviate the fuel shortage as over 30,000 lorry and tanker truck operators sat out a government requisition order to return to work on pain of prosecution.

Officials said the situation was improving in the main cities of Athens and Thessaloniki, but shortages were still reported on many holiday islands and destinations in northern Greece where thousands of tourists are stranded.

"If the trucks are able to load at refineries during the weekend a measure of supply should be restored by tomorrow," the chairman of Greek petrol station owners' federation Michalis Kiousis told Flash Radio yesterday.

Police units were escorting trucks to refineries to prevent interference from strikers, Net public television reported.

Five people including a police officer were injured last Thursday in a clash between striking truckers and riot police outside a refinery near Thessaloniki, northern Greece, the Athens News Agency reported.

Military trucks are resupplying critical sectors such as airports, electricity plants and hospitals, the government said.

A broad range of businesses from tourism car rentals to fruit growers have been badly hit by the protest which began last Sunday against plans by the government to liberalise the tightly-controlled freight sector.

But authorities warn that the greatest damage has been caused to the vital tourism industry which accounts for nearly a fifth of the recession-hit Greek economy, with thousands of travellers stranded by the protest and booking cancellations mounting.