Bahrain has deployed war planes to Jordan, the state news agency BNA said on Sunday, becoming the second Gulf Arab country to send warplanes to help in the fight against Islamist militants in Syria and Iraq.

Jordan has taken a leading role in conducting air strikes against Islamic State strongholds in Syria and Iraq since the militants killed a Jordanian pilot, Mouath al-Kasaesbeh, who was captured by the group after his plane crashed in Syria in December.

"A group of Bahraini Royal Air Force planes have landed in the Hashemite Kingdom of Jordan to participate in the international effort to annihilate terrorism," BNA said.

It did not say how many aircraft or what kind were sent.

The United Arab Emirates last week sent a squadron of F-16 jet fighters to Jordan to conduct air strikes against Islamic State alongside Jordanian planes.

The UAE had earlier joined a US-led coalition conducting air strikes against Islamic State suspended flights. But it had suspended flights, citing concerns about search and rescue capabilities, after the Jordanian pilot was downed.

Jordan's King Abdullah has vowed to avenge Kasaesbeh's killing and ordered his commanders to prepare for a stepped-up military role in the US-led coalition against Islamic State.

Many Jordanians fear being dragged into a conflict that could trigger a backlash by hardline militants inside the kingdom. But support for the military campaign has grown since Kasaesbeh's killing.

Jordanian military experts say the ability of the kingdom to sustain its air strikes would soon come under strain, given the 40 mid-life F16 jets the air force has at its disposal. US officials have told Reuters the United States was preparing plans to re-supply Jordan with munitions. – Reuters