WASHINGTON - There is growing evidence that battle-hardened extremists are filtering out of safe havens along the Pakistan-Afghanistan border and into East Africa, bringing sophisticated terror tactics that include suicide attacks.

The shift, according to U.S. military and counterterrorism officials, fuels concern that Somalia, in particular, could become the next Afghanistan - a sanctuary where al-Qaeda-linked groups could train and plan attacks against the West.

So far, officials say, the number of foreign fighters who have moved from southwest Asia and the Afghanistan-Pakistan border region to the Horn of Africa is small, perhaps two to three dozen.

But a similarly small cell of plotters was responsible for the devastating 1998 bombings of U.S. embassies in Kenya and Tanzania.

The cluster of extremists now believed to be operating inside East Africa could pass on sophisticated training and attack techniques gleaned from seven years at war against the United States and its allies in Iraq and Afghanistan, U.S. officials said.

"There is a level of activity that is troubling, disturbing," said Gen. William "Kip" Ward, head of U.S. Africa Command. "When you have these vast spaces that are just not governed, it provides a haven for support activities, for training to occur."

Ward added that U.S. officials already were seeing extremist factions in East Africa sharing information and techniques.

Several military and counterterrorism officials who spoke on condition of anonymity to discuss sensitive intelligence matters cautioned that the movements of the al-Qaeda extremists did not suggest they were abandoning the ungoverned Pakistan border region as a safe haven.

Instead, the officials view the shift more as an expansion of al-Qaeda's influence.

Last month, Osama bin Laden - who spent five years in Sudan before he was expelled in 1996 and relocated to Afghanistan - made it clear in an audiotape that al-Qaeda has set its sights on Somalia, an impoverished, lawless country in the Horn of Africa.

In the 11-minute tape released to Internet sites, bin Laden is heard urging Somalis to overthrow their new moderate Islamist president and to support their jihadist "brothers" in Afghanistan, Pakistan, Iraq, and the Palestinian territories.

Officials said that in recent years they have seen signs that terror techniques bearing al-Qaeda's signature are gaining ground in East Africa. The harbingers include coordinated suicide bombings in Somalia in October.

In the past, officials said, suicide attacks had tended to be frowned on by African Muslims.

But on Oct. 29, 2008, suicide bombers killed more than 20 people in five attacks in Somalia, targeting a U.N. compound, the Ethiopian consulate, the presidential palace in Somaliland's capital, and two intelligence facilities in Puntland.

The incident also marked the first time that a U.S. citizen - a young Somalian man from Minneapolis - carried out a suicide bombing.

The foreign fighters moving into East Africa complicate an already-rising crescendo of threats in the region. Those threats have come from the Somalia-based al-Shabab extremist Islamic faction and from al-Qaeda in East Africa, a small, hard-core group also known by the acronym EEAQ.

While not yet considered an al-Qaeda franchise, EEAQ has connections to the top terror leaders and was implicated in the August 1998 embassy bombings in Tanzania and Kenya that killed 225 people.

Al-Qaeda has the skills while al-Shabab has the manpower, said one senior military official familiar with the region. The scenario could become even more worrisome, the officials said, if the foreign fighters transplant their skills at bomb-making and insurgency tactics to the training camps in East Africa.