SANAA, Yemen -- Islamist extremists, many suspected of links to al-Qaeda, are engaged in battles with government forces for control of southern Yemen, attempting to create a stronghold near vital oil shipping lanes, Yemeni and U.S. officials said.
Over the past few weeks, the militants have taken over two towns and surrounding areas and appear to be pushing farther south, Yemeni security officials and residents said.
It appears as if al-Qaeda's regional affiliate is seeking for the first time to grab and hold large swaths of territory, adding a dangerous dimension to Yemen's political crisis.
U.S. and Yemeni officials worry that a loss of government control in the south could further destabilize this strategic Middle Eastern nation, which has been gripped for months by political paralysis and violent conflicts.
The government has not allowed journalists to visit Zinjibar, one of the towns seized by the militants. Provincial officials and tribal leaders describe it as a ghost town where streets are a canvas of destruction, struck by daily shelling, air assaults, and gunfire. There's no electricity, water, or other services.
Tens of thousands, mostly women and children, have fled the city. Men have stayed back only to protect their homes. The extremists man checkpoints and any semblance of authority or governance has vanished.
"They want to create an Islamic emirate," said Mohammed al-Shuhairi, 50, a journalist in al-Kowd, near Zinjibar. "I have lived through wars here in 1978, 1986, and 1994. But I have never seen anything as bad as this."
The extremists are mostly from various Yemeni provinces, but they include other Arabs and foreign fighters. They call themselves Ansar al-Sharia, or Supporters of Islamic Law, residents said.
In an April 18 interview on jihadist Web sites, Abu Zubayr Adel al-Abab, described as an official with al-Qaeda in the Arabian Peninsula, as the Yemen branch is called, said the militants identified themselves as Ansar al-Sharia.
"The name Ansar al-Shariah is what we use to introduce ourselves in areas where we work to tell people about our work and goals, and that we are on the path of Allah," said Abab, according to a translation by the London-based International Center for the Study of Radicalization and Political Violence.
The takeover of Zinjibar underscores the growing aggressiveness and confidence of al-Qaeda in the Arabian Peninsula, which appears to be taking advantage of political turmoil triggered by the populist rebellion seeking to oust President Ali Abdullah Saleh.
The crisis has deepened since he was wounded in a June 3 assault on his presidential palace, forcing him to fly to neighboring Saudi Arabia for treatment and raising doubts about his ability to rule.
Long before the death of Osama bin Laden, American officials considered al-Qaeda in the Arabian Peninsula among the most significant threats to U.S. soil and worried that it could create a launch pad to target the United States and its allies.
The capture of Zinjibar and nearby towns give the group access to the Red Sea and its vital oil shipping lanes. The militants are also well positioned to attack the port city of Aden, about 30 miles south.
U.S. State Department and intelligence officials have worried that al-Qaeda will exploit the worsening security situation in Yemen, and American officials have tracked the fighting in Zinjibar as a possible early test of the group's strength in the region.
State Department spokesman Mark Toner said al-Qaeda in the Arabian Peninsula's sizable presence puts the country on a different tier compared with other nations hit by political unrest.
"It's the reason why we've had such an ongoing, robust counterterrorism cooperation," Mr. Toner said. "But as we've said many times, that cooperation isn't hinged on one individual." Regardless of who leads Yemen, he said, "we're going to continue to work with the [current] government" to keep the terrorist group from gaining a foothold.
The rise of the Islamist extremists also complicates a political landscape crowded with several groups seeking power, including youth activists, the traditional political opposition, Saleh loyalists, powerful tribal leaders, and defected military generals.
Yemen's south has long provided a hiding place for al-Qaeda in the Arabian Peninsula militants, who are shielded by sympathetic, anti-regime tribes and mountains.
One of the group's top leaders, radical Yemeni American cleric Anwar al-Aulaqi, whom the Obama Administration has targeted for assassination, is thought to be in the south.