Addressing the 69th session of the UN General Assembly in New York on Thursday, Cameron said Iran “could be part of the solution” in defeating the terrorist group.

    “Iran's leaders could help in defeating the threat from ISIL,” Cameron said.

The British premier added that Iranian authorities “could help secure a more stable, inclusive Iraq, and a more stable, inclusive Syria,” and urged the international community to welcome actions on the part of Iran to combat the Takfiri militants.

Cameron noted that the international coalition against the threat imposed by ISIL must be inclusive. He also said he will hold a parliamentary debate Friday to discuss a possible British involvement in airstrikes against the ISIL positions in Iraq.

Cameron and Rouhani discussed ties and regional issues in a landmark meeting on Wednesday. It was the first bilateral talks between a UK prime minister and an Iranian president since Iran's Islamic Revolution in 1979.

The ISIL terrorists are in control of some areas in Syria and have captured large swathes of land in neighboring Iraq. Tehran has on several occasions voiced support for the Iraqi government since it began fighting against the ISIL in June.

ISIL has committed heinous crimes and threatened all communities, including Shias, Sunnis, Kurds, Christians and Izadi Kurds, during their advances.

According to a CIA source, more than 15,000 foreign fighters from more than 80 countries have gone to Syria to join militant groups. 2,000 of those fighters are believed to be Westerners, including at least 500 British nationals.

Observers have said the rise of ISIL can be directly attributed to the policies of Western countries, including the UK, in the Middle East region as they have been supporting insurgent groups in their fight against the Syrian government.