Iranian President Mahmoud Ahmadinejad is to make a one-day trip to neighbouring Afghanistan tomorrow to discuss with his counterpart Hamid Karzai how to stabilise the war-torn nation, Iran's Mehr news agency reported.
Mehr said the two men would "examine solutions to Afghanistan's problems" as Iran seeks to boost relations.
Ahmadinejad has repeatedly called for the withdrawal of US-led forces from Afghanistan, saying their presence was stoking the Taliban insurgency.
But despite their rivalry, Washington and Tehran are both sworn enemies of the extremist Sunni Muslim militia which ruled in Kabul from 1996 to 2001, before being overthrown in the US-led invasion.
The United States has made a number of efforts to involve all of Afghanistan's neighbours, including Iran, in restoring stability to Afghanistan.
But they have been complicated by the lack of diplomatic relations between Tehran and Washington and the standoff over Iran's nuclear programme.
Shiite Iran, which has close ethnic and religious ties with Afghanistan, has long suffered from the effects of opium production in its eastern neighbour, with easily available heroin fuelling a big rise in drug use at home.
Afghanistan is the source of 90 per cent of the world's heroin.