Philippine troops battle Islamist militants; 7 dead, 21 wounded

MANILA (Reuters) - Seven Philippine soldiers were killed and 21 wounded Thursday in the heaviest fighting in months between government troops and al Qaeda-linked militants on a remote southern island, an army spokesman said.

The militants of the Abu Sayyaf group also suffered heavy casualties when soldiers stumbled upon their main base on Jolo island, said Lieutenant-Colonel Randolph Cabangbang.

"We're sending helicopters to provide close air support as well as evacuate our casualties," Cabangbang told reporters, adding that soldiers battled the militants for five hours before capturing the base.

"Our troops were pursuing a small group of armed men who were holding captives when they found themselves in the middle of the Abu Sayyaf's main base. That would explain our losses."

The Abu Sayyaf, with an estimated strength of about 300 fighters, is the smallest but deadliest of several Muslim groups fighting the government of the majority Christian Philippines.

Since 2002, U.S. troops have been helping train and advise troops fighting the militants, and the Abu Sayyaf has been largely contained in recent years.

Cabangbang said there were an estimated 70 rebels in the base, near Patikul town, which served as the headquarters of militant leaders Radullan Saheron and Isnilon Hapilon.

Some Indonesian and Malaysian militants were believed to have been there, he added.

"We hit the militants' nerve centre, so there was heavy resistance," Cabangbang said.

Saheron and Hapilon are on a U.S. State Department wanted list for involvement in numerous murders and kidnappings, including three workers of the International Committee of the Red Cross in 2009 and an American missionary couple in 2001.

(Reporting by Manny Mogato; Editing by Robert Birsel)