Islamabad, Feb 17: Pakistan, Afghanistan and Iran have agreed to fight terrorism together, said President Asif Ali Zardari Friday, after a trilateral summit here.

The leaders of Pakistan, Iran and Afghanistan held their third trilateral summit since 2009. 

Iranian President Mahmoud Ahmadinejad and Afghan president Hamid Karzai along with Zardari participated in the summit that sought to boost economic and security cooperation among them. 

After the summit, Zardari said there was an agreement to fight terror together, Geo News reported.

"I deny this notion that any of our armed forces are directly or indirectly involved," he said to a query about the alleged involvement of Pakistani security agencies on the side of militants.

"Yes, I cannot deny that there is a residue in Pakistan of the war that was fought against the Soviet Union," he said.

"We cannot deny ... maybe there are people among our population who are involved in this, but this is a world problem," said Zardari.

Flanked by Karzai and Ahmadinejad, Zardari said: "The three presidents you see sitting together, we shall fight this menace. Nobody is more concerned or more involved in it than me personally." 

Ahmadinejad said foreign countries want to dominate the region and this should not be permitted.

"We should deny others the opportunity to interfere in our affairs," he said without elaborating.

Iran facing Western countries which accuse it of pursuing a nuclear weapons programme. Tehran says it needs nuclear power solely for civilian purposes.