Human Rights Watch has accused Sudanese troops of raping more than 200 women and girls in the troubled province of Darfur, calling for the "brutal attack" to be investigated as a "crime against humanity".

In a report released on Wednesday , the US-based rights group said a mass rape took place in the town of Tabit , casting doubt on the Sudanese government's repeated denials.

"The deliberate attack on Tabit and the mass rape of the town’s women and girls is a new low in the catalog of atrocities in Darfur," Daniel Bekele, Africa director at HRW, said.

At least 221 women and girls were raped when the Sudanese army launched three waves of attacks over 36 hours, beginning on October 30, according to the report, which is based on accounts from dozens of Tabit residents.

The report quoted a woman in her 40s whose three daughters were raped in their house, two of whom were under the age of 11.

"They raped my three daughters and me. Some of them were holding the girl down while another one was raping her. They did it one by one," the woman said.

Soldiers reportedly went from house to house, looting property, beating residents and arresting men who were taken to the outskirts of the town while women and girls were raped inside their homes, HRW said.

Credible information

During a two-month investigation, HRW documented 27 incidents of rape and obtained credible information on an additional 194 cases from the Tabit attacks.

Two army defectors told HRW that they had been ordered by their superior officers to rape women because they were rebel supporters even though there were no fighters near Tabit at the time of the attacks.

Khartoum repeatedly denied the allegations and refused to allow the UN-African Union force in Darfur, UNAMID, to carry out a full investigation.

The UN mission was denied access to Tabit after the reports first surfaced and when it entered the village on November 9, its team accused Sudan's military of trying to intimidate villagers to suppress the allegations.

HRW called on the Hague-based International Criminal Court (ICC) to open an investigation of the mass rape, which it said would amount to "crimes against humanity if found to be part of a widespread or systematic attack on the civilian population."

The ICC has already indicted Sudanese President Omar al-Bashir for war crimes, but he continues to travel to countries that are unwilling to arrest him.

Darfur has been wracked by conflict since 2003 when ethnic groups rebelled against the government.

According to the UN, at least 300,000 people have been killed and two million forced to flee their homes.