Islamists vow to fight any foreign troops in Somalia

* Islamists say will fight till last man

* Ethiopia to send help only with international mandate

By Ibrahim Mohamed

MOGADISHU, June 21 (Reuters) - Somalia's hardline al Shaabab Islamists will fight any foreign troops that come to the aid of the Horn of African government, a spokesman for the insurgent group said on Sunday.

Somali parliament speaker Sheikh Aden Mohamed Madobe on Saturday called upon neighbouring countries such as Djibouti, Kenya and Ethiopia to send military help to ward off a raging rebellion.

The African Union already has 4,300 peacekeepers in Somalia, but they are under constant attack by the Islamists that want to dislodge the government and impose a strict form of sharia, Islamic law.

"We tell our enemy that we do not fear any invasion from outside. We forced Ethiopia to withdraw from Somalia early this year and we shall do the same again," al Shabaab's Sheikh Ali Mohamud Rage told a press conference.

"We, the Somali young mujahideen, shall fight against any troops deployed here to help the government until our last holy fighter passes away. This is a clear signal that the so called government established by the enemy had totally failed."