Five American service members have died in a helicopter crash in the eastern Mediterranean, the US military says.

It says the aircraft suffered a mishap while refuelling as part of a routine training exercise.

The US has increased its operations in the region since the outbreak of the conflict between Israel and Hamas.

President Joe Biden paid tribute to the victims, saying service members were putting "their lives on the line for our country every day".

"We pray for the families of all our fallen warriors today and every day," he added.

The military statement did not specify where the aircraft was flying from or where the crash happened.

But the US has moved two aircraft carriers, as well as ships and jets, to the eastern Mediterranean over the past month.

The deployment reflects American concerns that the conflict between Israel and Hamas could draw in other parts of the region.

In particular, the US is eager to prevent Lebanon's powerful Hezbollah movement from joining the conflict.

It is backed by Iran, which also funds and arms Hamas.