The divers were detained on May 1 while working on a sunken ship 18 nautical miles off the disputed Abu Musa island in Gulf waters.

  

Abu Musa and the islands of Greater Tunb and Lesser Tunb are the  centre of a maritime dispute between the UAE and Iran.

  

The islands were seized by Tehran after British forces left the Gulf region in 1971 but are claimed by Abu Dhabi.

  

Disputes over the islands have in the past strained relations between the two countries which nonetheless maintain robust links, especially in trade.

  

Ahmadinejad's trip to the Emirati capital Abu Dhabi will be the first by an Iranian president to the UAE since the 1979 Islamic revolution.