New Delhi: Prime Minister Narendra Modi today held "substantive" talks with Iranian President Hassan Rouhani to boost cooperation in key areas of security, trade and energy, after which the two sides inked nine pacts, including one on double taxation avoidance.

The two leaders also deliberated on regional situations during their wide-ranging talks.

"Both leaders held substantive & productive discussion on cooperation in trade & investment, energy, connectivity, defence & security & regional issues," External Affairs Spokesperson Raveesh Kumar tweeted.

Addressing a joint press event with Rouhani, Modi said the visit by the Iranian president shows how the two sides want to deepen cooperation in key areas, including connectivity.

Giving details of their comprehensive talks, Modi said they discussed threats posed by terrorism, drug trafficking and other challenges.

On his part, Rouhani said, "We are determined to combat terrorism and extremism.

" The Iranian leader also said that regional conflicts must be resolved through diplomacy and political initiatives.

PM Modi also appreciated the way the Iranian leader provided leadership in developing strategically-important Chabahar Port.

Apart from tax pact, the two sides also exchanged instrument to ratify the extradition treaty as well as to simplify visa process.

Earlier, Rouhani was given a ceremonial welcome at Rashtrapati Bhavan.

In the morning, External Affairs Minister Sushma Swaraj called on Rouhani and discussed various issues with him.