The United States has delivered Hellfire missiles to the Lebanese army and will also provide it with light aircraft including an armed Cessna, the US ambassador to Lebanon said Friday.

David Hale, in a statement after meeting Prime Minister Tammam Salam, said the aircraft would be bought with Saudi funds recently pledged to the Lebanese army.

"Over the last two weeks, a series of accelerated shipments of American arms and armaments have arrived here," Hale said.

"This week brought the delivery of more Hellfire missiles to the Lebanese Army."

"The Lebanese government and army have requested additional aircraft from the United States: an armed Cessna and other light air support aircraft," the statement added.

"It is our intention to support those requests for additional aircraft, using funds generously made available to Lebanon by the Kingdom of Saudi Arabia."

Hale said another Cessna previously provided by the US to the Lebanese army would also be armed.

The pledges and arms deliveries come as several allies of Lebanon step up efforts to bolster its armed forces as the threat from jihadists in the region grows.

Lebanon was among 10 Arab states that pledged on Thursday to rally behind Washington against the Islamic State jihadist group that has terrorised parts of Iraq and Syria.

In August, Saudi Arabia pledged one billion dollars in funds to purchase military equipment for the Lebanese army, aid that came on top of three billion dollars it promised last year to buy French weapons.

The earlier weapons deal has dragged on, with no deliveries yet made, and the latest funding was intended to allow the speedy purchase and supply of much-needed materiel.

The additional funding was announced as the army battled an incursion from Syria by jihadists from several extremist groups, who are still holding hostage Lebanese soldiers and policemen.

Two of the soldiers have been beheaded by the Islamic State group, and efforts to negotiate the release of the remaining security forces, some of whom are being held by other jihadists, have stalled.

Hale said the weapons being provided by Washington "will help the army secure Lebanon's borders and defeat extremist groups that have crossed it".