French environment minister Francois de Rugy has slammed the "abnormal actions" of a Tunisian ro-pax that hit an anchored boxship off Corsica on Monday.

The 17,900-gt Cotunav ferry Ulysse (built 1997) steamed into Cyprus Sea Lines' 5,018-teu CSL Virginia (built 2005) on Sunday, spilling 600 tonnes of fuel in a slick stretching for miles.

French and Italian civil and military teams were working to contain the spead of the oil.