A purported Taleban spokesman says militants in Afghanistan captured a NATO soldier in southern Helmand province on Tuesday.
U.S.-led coalition forces in Afghanistan Wednesday, said they are investigating the claim.
Also Wednesday, a United Arab Emirates government official said a security guard with a UAE humanitarian mission in Afghanistan is missing.
It is not clear if the two incidents are linked.
Separately, an official in southern Afghanistan says police killed three militants in a clash overnight.
The chief of Mizan district in Zabul province Wednesday, said the battle erupted when Taleban militants attacked a police post.
In another development, senior U.S. military officials say Defense Secretary Robert Gates will ask for more support for the war in Afghanistan at a NATO meeting in Brussels this week.
Officials say Gates will call on Washington's European allies Thursday for more technical support to strengthen the Afghan army in its fight against Taleban militants.
About 50,000 U.S. and NATO troops are working with Afghan forces to put down a resurgent Taleban movement. Their efforts have been marred recently by civilian casualties.
Some information for this report was provided by AFP and Reuters.