Yemeni security forces have raided hospitals in Aden in search of suspected militants, threatening health care in the southern port city, an international rights group said Saturday.

Human Rights Watch also said government forces have stormed two hospitals in Aden at least five times this year, and on one occasion dragged a seriously wounded patient from intensive care after removing drainage tubes. The raids have forced one hospital to suspend its operations and others to turn patients away in fear of violence, the group said in a statement.

"Gunfights in hospitals put patients and medical workers at grave risk and threaten to shut down health care in Aden," said Letta Tayler, HRW's Yemen researcher. "Both security forces and their opponents are showing callous indifference to human life."

The head of Central Security Forces in Aden, Col. Abdul-Hafiz al-Saqqaf, denied that his agents had stormed hospitals, but said they went in to arrest three wanted outlaws who have attacked government checkpoints. Another security official in Sanaa denied those arrested are political opponents, calling them outlaws who are hired to sow chaos in Yemen.

In its report, Human Rights Watch said security officials describe the patients as suspects in serious crimes, including armed robberies and attacks against state security forces. The officials also said some of the suspects have links to the southern opposition movement, which is seeking greater autonomy for the former South Yemen.

Yemen's weak central government has been grappling with increased lawlessness in the country since the mass protest movement erupted last year against longtime leader Ali Abdullah Saleh, who was forced to step down in February. The political unrest compounded the country's already long list of problems — poverty, a southern succession movement and a growing threat from al-Qaida-linked militants.

Islamic extremists took over a swath of territory and several towns in southern Yemen over the past year before a military offensive pushed them out this summer, although the militants continue to carry out bombings and assassinations in Aden and other cities in the south.

Security forces are also engaged in a simmering conflict with opponents and supporters of Saleh who continue to stir up trouble for the central government, often challenging official decisions and in some cases defying orders. Saleh had warned that Yemen won't see stability if his supporters are removed from office.

Human Rights Watch said some of the raids on hospitals have turned violent, and have included attacks on guards and staff. Other raids sparked brief gunfire on hospital grounds.

In one incident earlier this month, security forces beat hospital guards and shot a 16-year-old fruit vendor in the head during an exchange of fire with gunmen trying to protect suspects from being arrested, HRW said.

The international humanitarian organization Medicins Sans Frontieres, or Doctors Without Borders, indefinitely suspended operations at its Aden hospital after another gunfight last month. It was the second time the organization had suspended its operations there this year.

HRW cited witnesses and an individual who investigated the attack said security forces and gunmen exchanged fire during a five-hour standoff at the MSF hospital, as the gunmen tried to prevent the arrest of two suspected militants. MSF was forced to evacuate 24 patients and close the facility, HRW said.

The governor of Aden told HRW that the wounded patients were "dangerous militants." Other health workers told HRW that nearly all hospitals in Aden now generally refuse to admit politically sensitive patients.