Tehran: The UN nuclear watchdog's top investigator will arrive in Tehran next week to hold more talks over Iran nuclear programme.

Olli Heinonen will ask Iran about Western allegations that the country had studied nuclear bomb designing, ISNA news agency reported on Friday.

Heinonen caused a diplomatic stir in February by indicating links in Iran between projects to process uranium, and modify a missile cone suitable for a nuclear warhead.

The International Atomic Energy Agency wants to clear suspicions about Iran's nuclear programme, which Iran insists is for peaceful purposes.