BERLIN, Jan 31 (Reuters) - The United States has written a strongly-worded letter to Germany and other NATO members urging them to send combat troops to dangerous areas in southern Afghanistan, a German newspaper reported on Thursday.

The Sueddeutsche Zeitung said U.S. Defense Secretary Robert Gates had last week written to his counterparts in NATO countries asking for 3,200 extra troops.

U.S. defense officials have regularly complained about the reluctance of European allies to dedicate more combat troops and equipment to Afghanistan where Taliban attacks have been rising.

In the letter, Gates warned of a looming division of the NATO alliance and of a loss in its credibility, the newspaper said. He also complained about the heavy burden on U.S. troops, added the newspaper which did not quote the letter directly.

The Defence Ministry in Berlin declined to comment on the report which the paper said was written in an unusually sharp tone.

According to its parliamentary mandate, Germany can send only 3,500 soldiers to the less dangerous North as part of the 40,000-strong NATO International Security Assistance Force (ISAF).

In exceptional circumstances German troops can be sent to other areas.

Earlier this week the Pentagon said it would press NATO's European members to send more troops to Afghanistan's violent South in response to a call from Canada for reinforcements.

Canada had threatened to pull out its 2,500 soldiers from Afghanistan early next year unless NATO sent reinforcements.

The United States has 29,000 troops in Afghanistan and earlier this month said it would add 3,200 Marines to the war zone.

Earlier this month Gates sparked tensions by criticising some NATO forces in Afghanistan, saying they did not know how to fight a guerrilla insurgency. (Writing by Madeline Chambers; editing by Sami Aboudi)

AlertNet news is provided by