NATO's top official said on Thursday that the U.S.-led alliance had no plans to intervene in Libya, and any action would anyway require the go-ahead from the United Nations.

"NATO, as such, has no plans to intervene. We have not received any request in that respect and, anyway, any action should be based on a clear U.N. mandate," Secretary General Anders Fogh Rasmussen told journalists.

Rasmussen, answering questions at a news conference after talks with Ukrainian President Viktor Yanukovich, said he did not consider the Libyan crisis to be a direct threat to NATO or its allies.

But he acknowledged it was giving rise to migration and refugee issues that were having a "negative impact" on Libya's neighbours.

Reuters