At least 27 people have been killed in fierce clashes between Hamas security forces and armed members of the Dughmush family in Gaza City, in one of the most violent internal confrontations since the end of major Israeli operations in the enclave.

Masked Hamas gunmen exchanged fire with clan fighters near the city's Jordanian hospital, witnesses said.

A senior official in the Hamas-run interior ministry said security units surrounded them and engaged in heavy fighting to detain them. The ministry said eight its members were killed in "an armed assault by a militia".

Medical sources said 19 Dughmush clan members and eight Hamas fighters had been killed since fighting began on Saturday.

Eyewitnesses said the clashes erupted in the Tel al-Hawa neighbourhood in southern Gaza City after a Hamas force of more than 300 fighters moved to storm a residential block where Dughmush gunmen were entrenched.

Residents described scenes of panic as dozens of families fled their homes under heavy gunfire, many of them displaced multiple times during the war.

"This time people weren't fleeing Israeli attacks," one resident said. "They were running from their own people."

The Dughmush family, one of Gaza's most prominent clans, has long had a tense relationship with Hamas, and its armed members have clashed with the group on several occasions in the past.

The Hamas-run interior ministry said its forces were seeking to restore order, warning that "any armed activity outside the framework of the resistance" would be dealt with firmly.

Both sides traded accusations over who was responsible for triggering the clashes.

Hamas earlier said Dughmush gunmen killed two of its fighters and wounded five others, prompting the group to launch an operation against them.

However, a source from the Dughmush family told local media that Hamas forces had come to a building that once served as the Jordanian Hospital, where the family had taken refuge after their homes in the al-Sabra neighbourhood were destroyed in the recent Israeli attack.

The source claimed that Hamas sought to evict the family from the building to establish a new base for its forces there.

Hamas has recalled about 7,000 members of its security forces to reassert control over areas of Gaza recently vacated by Israeli troops, according to local sources.

Reports suggest armed Hamas units have already deployed across several districts, some wearing civilian clothes and others in the blue uniforms of the Gaza police. The Hamas media office denied it was deploying "fighters in the streets".