Iran has released two Kuwaitis held for a month, clearing them of spying, the semi-official Mehr news agency reported on Sunday.

The arrests took place amid tense relations between Shiite Muslim Iran and its Sunni Arab neighbours following unrest in Bahrain by majority Shiites, which Manama had blamed on Tehran.

Mehr quoted Iran's ambassador to Kuwait, Ruhollah Qahremani, as saying the men had illegally worked as journalists in Iran while travelling on tourist visas, but speculation they were spies had been wrong.

In a sign Iran is seeking to soothe relations with the Gulf Arab states, Intelligence Minister Heydar Moslehi met Saudi Crown Prince Nayef last week - the first official contact since the United States accused the Islamic republic of backing a plot to kill the Saudi ambassador to Washington.