Turkey has challenged Russia to prove its claim that Ankara shot down a Russian plane in order to protect its oil trade with Islamic State (IS).

"If you allege something you should prove it," Turkish President Recep Tayyip Erdogan said.

He was responding to the accusation by Russian President Vladimir Putin, who also said last week's downing of the plane was a "huge mistake".

The Turkish government has refused to apologise for the incident.

One Russian pilot was killed and the other rescued after Russia's Su-24 bomber was shot down by a Turkish F-16 fighter on the Syrian border on 24 November.

A Russian marine was killed during the rescue operation in north-western Syria.

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

The US state department has said evidence from Turkish and US sources indicates the aircraft did violate Turkish airspace.

Turkey has denied any ties to IS and is part of a US-led coalition carrying out air strikes against the militant group.

"You should put your documents on the table if you have any. Let's see the documents,"  Erdogan said.

"We are acting with patience. 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."

President Erdogan also vowed to step down if the allegation that Turkey was buying oil from IS proved true, suggesting that President Putin should do the same if he was wrong.

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

Turkey is a vehement opponent of  Assad and has been accused of turning a blind eye to jihadist fighters crossing from its territory into Syria.

Until a few months ago, Turkey was reluctant to play an active role in the coalition against IS. However, in August it allowed the US-led coalition to begin using its airbase at Incirlik.

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.

IS earns much of its money from illegal sales of oil. However, Turkey has staunchly denied that it is involved in the trade.

"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,"  Putin said at a news conference in Paris on Monday.

He said Russia had received more information to show that IS oil was passing through Turkish territory.

Turkey and Russia have important economic links. Russia is Turkey's second-largest trading partner, while more than three million Russian tourists visited Turkey last year.

President Erdogan said Turkey would act "patiently, not emotionally" before deciding its response to the economic sanctions.