NATO has no plans to intervene in the unrest in Libya and has received no request to do so, Secretary General Anders Fogh Rasmussen said after talks in Ukraine on Thursday.

"I would like to stress that NATO has no plans to intervene and we have not received any request," Rasmussen said after talks with Ukrainian President Viktor Yanukovych.

"In any case, any action should be based on a clear United Nations mandate," he added.

Former Cuban leader Fidel Castro claimed Tuesday the United States was about to order NATO to invade Libya to control its oil interests.

Washington "will not hesitate to give the order for NATO to invade that rich country, perhaps in the coming hours or days," he claimed in an article written for official state media.

Both the United States and the European Union are currently considering fresh sanctions against Libyan leader Moamer Kadhafi's regime, but neither has officially suggested the use of force.

US Defence Secretary Robert Gates said in an interview published Wednesday that the United States may find it difficult to implement a no-fly zone over Libya that would put a halt to the reported bombing of anti-Kadhafi protesters.

Gates, however, said such a zone might be enforced by France or potentially Italy, which have sufficient forces on the region.

On Thursday, Rasmussen said the current turmoil threatened to impact Libya's neighbours, but posed no direct threat to NATO or its allies.

"I do not consider the situation in Libya a direct threat to NATO or NATO allies," Rasmussen said.

"But of course there may be negative repercussions. Such upheavals may have impact on migration, refugees. That also goes for neighbouring countries."

More than 30,000 Tunisian and Egyptian migrants have fled to their home countries from Libya since Monday, the International Organization for Migration said Thursday.