Iraqi troops are poised to launch a ground offensive against the Islamic State (Isis) to retake swathes of land seized by the jihadists last year, according to the US coordinator for the anti-IS international coalition John Allen.

The major counter-offensive is expected to come weeks after Kurdish forces drove the Islamist militants out of the Syrian border town of Kobani with the help of the US-led coalition's airstrikes,

"In the weeks ahead, when the Iraqi forces begin the ground campaign to take back Iraq, the coalition will provide major firepower associated with that," Allen said in an interview with Jordan's official Petra news agency, adding that the US "is doing all it can to deliver its support as quickly as possible".

Jordan, one of the Arab nations that is part in the coalition, said it carried out 56 airstrikes on IS logistics sites and hideouts after the Islamist group burned alive one of its military pilots, 26-year-old Moaz al-Kasasbeh.

A gruesome video of Kasasbeh's execution was published online by IS last week, causing a backlash in the Arab Kingdom.

IS militants said that one of Jordan's strikes killed US aid worker Kayla Mueller - but the claim is still unverified.

US secretary of state John Kerry said the air offensive was beginning to win back territory. He told the Munich Security Conference that 2,000 air raids have taken place since the coalition's formation in August, which allowed Iraq to retake some 700 square kilometres of territory or "one-fifth of the area they had in their control".