Iraqi authorities say the Islamic State (Isis) is getting supplies of arms and ammunition by planes, a week after a weapons-laden Russian plane was forced to land in Baghdad.

Hakim Zalmi, the chief of Iraq's key security and defence committee, said some countries are supplying weapons to the Sunni insurgents, who are currently terrorising Iraq and Syria capturing vast swathes of territories, by violating Iraqi airspace. However, he did not name the countries.

"Some countries are delivering weapons to IS by using airplanes in Tel Afar airport, near Mosul. I am asking the Iraqi air force to shell Tel Afar airport, together with any other airports under the control of IS in Iraq," said the Iraqi official, according to the Kurdish daily Rudaw.

The report comes a week after a Russian cargo plane carrying about 40 tonnes of medium and light weapons originating from an unknown sender landed at Baghdad International Airport.

An investigation has been ordered into the matter.

"Abadi [General Commander of Iraqi Armed Forces] asked the defence minister to investigate the unknown arms shipment, which landed at Baghdad International Airport and order to confiscate the weapons onboard," a security source was quoted as saying at the time of confiscation.

Zalmi, the Iraqi security committee chief, insisted this was not the first time a plane was violating Iraqi airspace.

"The plane that landed in Baghdad last week was filled with weapons, and it was not the first plane to land, breaching Iraqi air space," he said. "An investigation is still ongoing regarding that case."