Up to 25 troops were missing and feared dead after Islamic militants armed with rockets overran a remote military outpost close to the Afghan border, the military said Wednesday. It claimed 40 attackers were killed in the fight.

"About 200 militants charged the fort from four sides" late Tuesday, said army spokesman Maj. Gen. Athar Abbas. "They broke through the fort's wall with rockets."

"Fifteen of the troops in the base escaped and they have reached (the town of) Jandola while 25 others have scattered and there is no news how many of them were martyred or fled," he said.

The border region has emerged as a front line in the war on terror since Pakistan allied itself with the U.S. following the Sept. 11, 2001, terrorist attacks. Washington has given Pakistan billions of dollars in aid to help government forces battle militants.

A total of 40 members of the paramilitary Frontier Corps were manning the post at the time of the attack, Abbas said, adding that government artillery was shelling the region.

Forty attackers died in the assault, he said. It was not immediately possible to verify the army's claim. In the past, the rebels have given much lower figures for their own casualties.

The outpost is one of several dozen such bases located along South Waziristan's mountainous border with Afghanistan.

The U.S. hopes that elections set for Feb. 18 will help stabilize Pakistan as it faces rising attacks by militants. On Tuesday, Pakistan's government urged opposition leaders to refrain from holding rallies ahead of the elections, citing an escalating terrorist threat.