ANKARA • Turkey has challenged Russia to prove its claim that Ankara shot down a Russian bomber to protect its oil trade with the Islamic State in Syria and Iraq (ISIS), and a defiant President Recep Tayyip Erdogan has vowed to quit his post if Moscow could provide proof.

"If you allege something, you should prove it," President Erdogan said in response to the accusation by Russian President Vladimir Putin, who also said last week's downing of the plane was a "huge mistake".

Turkey has denied any ties to ISIS, which earns much of its money from illegal sales of oil, and is part of a United States-led coalition carrying out air strikes against the militant group.

"You should put your documents on the table if you have any," Mr Erdogan said. "It is not positive for the two countries, which have reached a position which could be regarded as a strategic partnership, to make emotional statements."

Mr Erdogan said he would step down if the ISIS oil claim was verified, suggesting Mr Putin should do the same if he was wrong.

"If such a thing is proven, the nobility of our nation would require that I would not stay in office," Mr Erdogan was quoted by the state-run Anatolia news agency as saying on the sidelines of the United Nations climate talks in France, which Mr Putin is also attending.

Mr Putin has refused to meet the Turkish leader in Paris.

Turkish Prime Minister Ahmet Davutoglu told a news conference yesterday that Turkey would continue in its efforts to expel ISIS

militants from the area on the Syrian side of the border between the two countries. He also reiterated a call to Russia to open channels of military communication between the two countries to prevent incidents similar to the downing of the warplane by Turkish jets along the Syrian border last week.

Russia has imposed sanctions on Turkey over the downing of the plane, including restrictions on imports of Turkish food and an end to visa-free travel.

"We have every reason to think that the decision to shoot down our plane was dictated by the desire to protect the oil supply lines to Turkish territory," Mr Putin said at a news conference in Paris on Monday.

The Turkish government has refused to apologise for the jet incident.

One Russian pilot was killed and the other rescued after the Su-24 bomber was shot down by a Turkish F-16 fighter on the Syrian border last Tuesday. A Russian marine was killed during the rescue operation in north-western Syria.

Turkey says the jet entered its airspace, an accusation Russia denies.

Russia has been carrying out air strikes in Syria, targeting rebels against Syrian President Bashar al-Assad, including ISIS.

AGENCE FRANCE-PRESSE, REUTERS