LONDON - Britain is investigating an incident in Afghanistan two months ago in which two Danish soldiers may have been killed by British "friendly fire", the Ministry of Defence said on Monday.

The Danish soldiers were killed on September 26 in the southern province of Helmand, where both British and Danish troops operate.

The deaths were first reported to have been the result of a firefight with Taliban militants, but three days later the Danish army said "friendly fire" may have been to blame.

Denmark said at the time that a joint investigation would be opened, but Britain only confirmed that on Monday.

"We are working closely with the Danish government to establish the details and the causes of this incident," a ministry spokesman said. "A board of inquiry has been opened."

The spokesman would not confirm whether the deaths occurred as a result of ground fire or an air attack, saying it was still uncertain that British troops were definitely involved.

"It would not be appropriate to comment further before the board of inquiry is complete," he said.

Denmark has about 550 troops operating in Afghanistan as part of NATO's international stabilisation force.