BAGHDAD/ERBIL, Iraq (Reuters) - Iraq’s Prime Minister Haider al-Abadi demanded on Wednesday that Kurdish authorities “cancel” the outcome of the independence referendum in northern Iraq, as a condition for dialogue to resolve an escalating crisis.

In a speech to parliament, Abadi renewed his ultimatum to Masoud Barzani’s Kurdistan Regional Government (KRG) to hand over control of international airports by Friday or face a ban on direct international flights to the Kurdish region.

People in northern Iraq voted overwhelmingly in favour of independence in Monday’s non-binding referendum. Any idea of secession is bitterly opposed by the governments in Baghdad, Turkey and Iran. The United States pressed Kurdish leaders to call off the poll.

“We won’t have a dialogue about the referendum outcome,” Abadi told parliament. “If they want to start talks, they must cancel the referendum and its outcome.”

His demand was rejected by KRG Transport Minister Mowlud Murad on Wednesday. He told a news conference in the Kurdish capital Erbil that keeping control of airports and maintaining direct international flights to Erbil was necessary for the fight against Islamic State militants.

Kurdish leaders say the referendum was held to give them a mandate to negotiate the peaceful secession of their region with Baghdad and Iraq’s powerful neighbours Iran and Turkey.

Murad expressed the hope that the crisis could be resolved by Friday, saying it would damage Kurdistan’s economy.

The Iraqi Civil Aviation Authority sent a notice on Wednesday to foreign airlines telling them international flights to Erbil and Sulaimaniya in the Kurdish region would be suspended on Friday at 1500 GMT and only domestic flights allowed.