* Bagher Asadi arrested mid-March in Tehran - sources
* No details on who arrested him or why
Iran's foreign minister said he believed the detention of a former diplomat linked to the country's reformists was caused by a "misunderstanding" and defended the man's record, Iranian media reported.
Bagher Asadi, who was a senior diplomat at Iran's U.N. mission in New York before becoming a director at the secretariat of the D8 group of developing nations in Istanbul, was arrested mid-March in the Iranian capital, sources told Reuters this week.
It was not clear where Asadi was being held, who arrested the 61-year-old diplomat or on what grounds, the sources said.
Iranian Foreign Minister Ali Akbar Salehi confirmed Asadi's arrest, the ISNA news agency reported on Thursday.
"It's unfortunate that there has been a misunderstanding regarding Mr. Bagher Asadi, one of the highly skilled and valuable experts in the foreign ministry who has a good track record and from whom we have seen nothing but efforts to secure the country's interests, and we are hopeful this misunderstanding will be resolved," Salehi said.
Salehi did not say who had arrested Asadi.
"From what we know of Mr. Bagher Asadi, we know him as a devout person ... and a very reputable official with a brilliant record," Salehi said. "God willing, this misunderstanding will be resolved and by the grace of God he will be freed."
Iran's reformists have been sidelined since Mahmoud Ahmadinejad, the conservative former mayor of Tehran, won the presidential election in 2005, replacing reformist Mohammad Khatami.
Opposition leaders Mehdi Karoubi and Mirhossein Mousavi, both candidates in the 2009 presidential election, are under house arrest following mass protests over alleged fraud in the re-election of Ahmadinejad that year.
Last month Ahmed Shaheed, the U.N. special rapporteur on human rights in Iran, said Tehran's silencing of journalists and opposition leaders could jeopardize the legitimacy of the presidential election in June.
In January 2004, Asadi wrote an opinion piece that ran in the New York Times in which he made clear his affinities with the reformist philosophy of Khatami.
Some analysts say Iran's Islamic clerical leadership is worried about the risk of serious unrest in the June 14 election and is cracking down in advance.