Libya's oil minister has reportedly defected and fled to Tunisia.

Shokri Ghanem, who also chaired the National Oil Corporation, is said to be on his way to the Tunisian capital, Tunis.

Hoda Abdel Hamid, one of Al Jazeera's correspondents in Libya, said a border guard confirmed the defection.

"He told us the minister had crossed into Tunisia two days ago and that he was alone, not with his family," she said.

"He mentioned he had tried to cross before but was held in Libya. We cannot confirm this."

Rebels fighting to end the 41-year-old rule of Muammar Gaddafi, Libya's embattled leader, also said they had information that Ghanem, 68, had defected.

However, rebels and Arab media reported on a previous occasion that Ghanem had stepped down, but he later re-appeared and said he was in his office and working as usual.

If confirmed, Ghanem would be the latest high profile Libyan official to leave the Gaddafi government. In March, Gaddafi's foreign minister, Moussa Koussa, defected.

Ghanem has been in charge of the oil ministry since 2006 and was previously prime minister. His oil ministry is the biggest income generater for the country. Libya has Africa's largest oil reserves, at 41.5 billion barrels.

Rebels have taken Benghazi and the oil-producing east of the North African country, their insurgency helped by a NATO bombing campaign sanctioned by the United Nations to protect civilians.