Italy signaled it would most likely allow the use of its airbases and airspace for strikes against Islamic State militants in Libya if the United States asks, Defence Minister Roberta Pinotti said on Wednesday.

"The government is ready to consider positively a request to use airbases and national airspace, and support the operation, if it is believed that it would lead to a more rapid and effective conclusion of the ongoing action," Pinotti said in testimony to the lower house of parliament.

US planes began bombing Islamic State targets in Libya on Monday at the request of the UN-backed government in Tripoli to help push militants from their former stronghold of Sirte.