US weighing 'military options'

The US is weighing potential military options in Libya as Islamic State jihadists expand their influence in the north African nation roiled by political instability, a Pentagon official said Wednesday.

The growing IS presence in Libya is a "significant concern" and the United States is assessing how best to respond to the group's "metastasis" from Iraq and Syria, said Pentagon press secretary Peter Cook.

"We're looking at military options, a range of other options as... the situation in Libya unfolds," Cook said.

"We want to be prepared, as the Department of Defense always wants to be prepared, in the event that ISIL in Libya becomes more of a threat than it is even today," he added, using an acronym for the IS group.

Reluctant to see its 17-month air campaign against the IS group in Iraq and Syria spread to a third country, the US has repeatedly stressed the importance of finding cooperative local partners in Libya.

The IS group is reported to have at least 3,000 fighters in Libya.