BETHLEHEM (Ma'an) -- A group of Shiite worshipers say masked police violently raided a religious service in the northern Gaza Strip on Saturday, prompting furious denials by the Hamas-dominated government in the territory.

Around 20 followers of the Shia branch of Islam were performing a ceremony for Ashura, the commemoration of the death of Prophet Muhammad's grandson Hussein, when masked police stormed the private home in Beit Lahiya, they told Palestinian human rights groups.

Security officers beat the worshipers with clubs, and took them for interrogation at a police station where they were further assaulted, they told the Gaza-headquartered Palestinian Center for Human Rights.

Several sustained fractures and bruises from the beating and were taken to Balsam and Kamal Odwan hospitals, PCHR said.

The Gaza-based Al Mezan Center for Human Rights said that upon leaving hospital, they were handed notifications to go to the interior security headquarters in northern Gaza.

A Shiite man, who asked to be referred to as M. M., told Ma'an on Sunday "to be assaulted by Hamas security is outrageous because we are not against the law, we respect it."

"These rites concern freedom of religion ... we are Muslims like all the people in Gaza."

The Shia will continue exercising their religious rites, which they are proud of, he said.

Another Shiite man, using the name Abu Zeinab, said security forces dispersed the religious ceremony after alleging it did not have the proper license, but denied the group were assaulted.

Hamas officials initially refused to comment on the matter, and said Sunday they considered the account to be a fabrication by Ma'an.

On Monday, the Gaza interior ministry published a press statement denying the account relayed by human rights groups.

"Police tracked an illegal group with corrupted views that were planning to commit crimes," the ministry said in its version of the Saturday night raid.

The ministry also said Palestine is a Sunni country where Shiism does not exist.

"We respect all the doctrines around the world, especially the Shiite school, and we don’t intervene in what they believe and we don’t want them to intervene in our beliefs as well," the statement said.

While vowing to study allegations of human rights abuse, the interior ministry warned human rights groups to consult official sources and not believe just any account of events.

The ministry also called on the media to work for positive national goals.

PCHR urged the Gaza government to open an investigation into "the use of excessive force by the security officers ... and to bring the perpetrators to justice."

The raid broke Palestinian laws on freedom of belief and expression, and a prohibition on raiding private homes without a judicial order, Al Mezan said.

Meanwhile, M. M. told Ma'an that Shiites would "complain about Hamas to Iran, which supports the movement in Gaza."

Abu Zeinab complained that Iran did not offer sufficient support for Shiites in Gaza. While the Shia are harassed by Hamas, they faced worse suppression under Fatah-dominated Palestinian Authority rule prior to the 2007 split between the governments, he added.

Hamas premier in Gaza Ismail Haniyeh is due to visit Iran in early February. The Sunni group is believed to receive considerable support from the Shia power, but the uprising in Syria, Iran's regional ally, has strained their historic ties.