European countries locked in a diplomatic row with Libya should remember that their energy firms have interests in the North African country, Libya's top energy official said in an interview.

Libya has stopped issuing entry visas to citizens of most European countries in retaliation for Switzerland barring entry to senior Libyans including leader Muammar Gaddafi and members of his family.

"We hope this crisis will be resolved," Shokri Ghanem, the head of Libya's state energy firm NOC and the country's OPEC representative, told Reuters in an interview late on Sunday.

"Regarding the oil sector, we think European companies have many interests in Libya and these countries should know their interests," Ghanem said.

"They should also think of these interests and investments in energy because good relations with Libya would help European companies run their businesses in Libya easily," he said.

European energy firms with investments in Libya, home to Africa's largest proven oil reserves, include BP, Italy's ENI and Spain's Repsol.

Ghanem had previously warned that the business interests of U.S. firms could be damaged over the diplomatic row, but he has not before made any public mention of repercussions for European companies.

He issued the warning to U.S. firms including ConocoPhillips and Exxon Mobil after a U.S. official made an acerbic comment about a speech in which Gaddafi called for a "jihad" against Switzerland.

However, that dispute appears to have been resolved after the U.S. official apologised for his remarks and the apology was accepted by Tripoli.

Libya's long-running spat with Switzerland -- which is at the heart of the dispute with European countries -- began in July 2008 when police in Geneva arrested one of Gaddafi's sons, Hannibal, at a luxury lakeside hotel.

The charges, of mistreating two domestic employees, were later dropped but the arrest angered Libya, which halted oil exports to Switzerland and withdrew its deposits from Swiss banks in protest.