Brig. Gen. Nicolas Matern, Multi-National Corps Iraq deputy commander, said with a U.N. mandate that offered the countries authorization to operate in Iraq set to expire at year's end, coalition forces are set to be significantly depleted, The Times of London reported Saturday.

Matern said the mandate expires on Dec. 31 and 13 countries including Japan and South Korea will be removing their Iraq forces in preparation for that date.

"We are going to say farewell to 13 different nations in the space of two and a half weeks," Matern, whose group supervises all coalition partners of the U.S. military, said.

Matern said the loss of the 13 countries follows similar troop withdrawals by other former coalition members.

"We started off with 35 countries but it has steadily been going down ... As from December it is going to go all the way down," he said.

The military official told The Times that the only remaining U.S. allies in Iraq after the mandate's expiration will be Australia, Britain, El Salvador, Estonia and Romania.