BAGHDAD (Reuters) - Islamic State militants attacked Iraqi soldiers near a hospital in southeast Mosul on Wednesday, an army officer and the jihadist group’s new agency said, trying to repel the army’s deepest advances of the seven-week Mosul campaign.

Iraqi forces backed by tribal militias during battle to retake a village from the Islamic State on the eastern bank of the river Tigris, Iraq December 7, 2016. REUTERS/Mohammed Salem

The fighting came a day after the army’s operations commander for Mosul said soldiers surged into the city and took over the Salam hospital, less than a mile (1.5 km) from the Tigris river which divides eastern and western Mosul.

Tuesday’s rapid advance marked a change in military tactics after more than a month of grueling fighting in the east of the city, in which the army has sought to capture and clear neighborhoods block by block.

But it left the attacking forces exposed, and the Islamic State news agency Amaq said on Wednesday some of them were surrounded. It said a suicide bomber blew himself up near the hospital, killing 20 soldiers. Eight armored personnel carriers were also destroyed in the fighting, Amaq said.

There was no official Iraqi military comment on the fighting but the army officer, whose forces were involved in the clashes, said they had come under multiple attacks by suicide car bombers in the Wahda district where the hospital is located.

“We managed to make a swift advance on Tuesday in al-Wahda but it seems that Daesh fighters were dragging us to an ambush and they managed later to surround some of our soldiers inside the hospital, he told Reuters by telephone, requesting anonymity because he was not authorized to speak to media.

He said an armored regiment and counter terrorism units, backed by U.S.-led air strikes, were sent to support the stranded troops early on Wednesday and had opened up a route out of the neighborhood.

“They have secured the position, evacuated the wounded and pulled out the destroyed military vehicles from around the hospital,” he said, adding that they were coming under fire from snipers and rocket-propelled grenades.

Amaq said it attacked the relief convoy in Sumer district, south of Wahda near the outer edge of the city.

Iraqi forces have been battling for seven weeks to crush Islamic State in Mosul. The city was seized by the militants in 2014 and is the largest in Iraq or Syria under their control.

Defeating Islamic State in Iraq’s biggest northern city would help roll back the group’s self-styled caliphate over large parts of both countries.