By Fumbuka Ng'wanakilala

DAR ES SALAAM (Reuters) - Tanzania said on Sunday it would seek a stronger mandate for peacekeepers in Sudan's strife-torn Darfur region after seven of its troops were killed in an ambush on Saturday.

The head of U.N. peacekeeping operations, Herve Ladsous, told Reuters in Paris that the situation in the area was "totally unacceptable".

Tanzania said 36 members of its contingent of soldiers and police had been ambushed by rebels some 20 km (12 miles) from Khor Abeche in South Darfur. Seventeen others were wounded, including two women.

"We are communicating with the U.N. on the possibility of strengthening the mandate of peacekeepers in Darfur to enable our troops to protect themselves against attacks," Tanzania's army spokesman, Kapambala Mgawe, told reporters in the east African country's commercial capital, Dar es Salaam.

"We want our troops in Darfur to be able to use force to enforce peace and defend themselves against future ambushes from rebels."

Tanzanian President Jakaya Kikwete expressed his grief over the casualties.

A Tanzanian general was last month appointed commander of the joint African Union/United Nations UNAMID force in Sudan, whose Tanzanian contingent numbers 875.

Law and order has collapsed in much of Darfur, where mainly African tribes took up arms in 2003 against the Arab-led government in Khartoum, which they accuse of discriminating against them.

Ladsous, who said he had been in Darfur about 10 days ago, said the deterioration of security was a major concern.

"We've had 300,000 more displaced persons since January this year, which is double the figure we had for the two previous years ...

"It is absolutely unacceptable that peacekeepers be deliberately, as they were, ambushed and targeted," he said. "We want to know who is behind this."

Violence has surged since January as government forces, rebels and Arab tribes, armed by Khartoum early in the conflict, fight over resources and land. Peacekeepers have been attacked several times as they tried to find out what was happening on the ground.

Diplomats say the more than 16,000 peacekeepers are struggling with equipment problems, poor training of some contingents and the reluctance of some governments such as Egypt to send their soldiers into dangerous areas.

(Additional reporting by Alexandria Sage in Paris; Writing by James Macharia; Editing by Kevin Liffey)