GARISSA, Kenya, June 13 (Reuters) - Kenyan security forces will join Somali and Ethiopian troops searching for two Kenyan policemen believed abducted by Islamist fighters and taken into Somalia, a top Kenyan police commander said on Wednesday.

The pair vanished on Sunday on the remote border, where tensions are running high over the arrest of scores of suspected Somali Islamists trying to enter Kenya after they were routed from Mogadishu in January by Somali and Ethiopian troops.

Security officials from the three countries have agreed to pursue talks with local clan elders to try to win the officers' release, but a joint force will also start searching.

"We shall use diplomacy, but our troops will also join Ethiopian and Somali forces and move into Somalia," Anthony Kibuchi, Kenya's Northeastern Police Commander, told Reuters.

Armoured cars and military helicopters were being prepared at an army camp in the border town of Mandera, where one local aid worker said the policemen were believed to have been taken to Luuq, a town about 30 km (18 miles) away inside Somalia.

Kenya rushed extra security personnel to the border earlier this year when members of a hardline Somali Islamist movement fled south and west from Mogadishu after losing a two-week war.

Many tried to slip into Kenya, but scores were caught. The government has been criticised for sending some back to Somalia in a case two rights groups dubbed an "African Guantanamo".