In his first visit to Afghanistan as Iran's president, Hassan Rohani has called for regional unity while at the same time saying international forces brought "destruction" to Afghanistan.

Rohani and other regional leaders joined Afghanistan's Hamid Karzai in Kabul on Thursday in celebrating the Persian New Year, Nowruz.

Rohani says Afghanistan has been occupied twice by foreign countries — a reference to the Soviet Union in the 1980s, and the U.S. and allied troops who ousted the Taliban.

He says "they brought violence and extremists to this country."

Iran opposes a security agreement that would allow thousands of foreign forces to stay in Afghanistan beyond the end of 2014.

Karzai has refused to sign the pact, but the main three contenders in elections to replace him said they would.