Iran's Ahmadinejad in Afghanistan, Gates departs

However, despite their suspicions, Western countries have praised Tehran's efforts in combating the drug trade. Iran has a serious heroin addiction problem, while Afghanistan produces nearly all the world's opium used to make the drug.

Karzai is due to fly to Pakistan later on Wednesday, meeting the leadership of another big neighbour.

(Reporting by Phil Stewart and Sayed Salahuddin; writing by Peter Graff)