NEW DELHI: Two Nepali maids who say they were repeatedly raped and tortured by a Saudi diplomat in India are demanding justice, despite the fact that the envoy has diplomatic immunity and has returned home, Amnesty International India said on Thursday.

The two women, aged 30 and 50, were rescued in September by Indian police from a luxury apartment in the outskirts of New Delhi after a tip-off from an anti-human trafficking group and the Nepali embassy.

They said they were gang raped, assaulted, tortured and starved while held captive for over three months. On one occasion they were raped by eight men, they said. Medical examinations showed evidence of rape and sodomy.

"For me, the sooner I get justice the better. Three countries are involved in this. We have faced so many problems and we struggled a lot, and we need justice," the rights group quoted one of the women as saying in an interview at a shelter where they are now living in Nepal's capital Kathmandu.

"Arrest whoever is involved ... It is like a nightmare for us. The only thing I want is justice and for them to be put in jail," added the woman, who cannot be named under Indian law.

The Saudi Embassy in New Delhi has denied the allegations, and the accused diplomat returned to Riyadh on Sept. 16, a week after the women were rescued.

Related: Saudi diplomat accused of rape withdrawn from India

India's foreign ministry said he was protected under the Vienna Convention, which grants envoys diplomatic immunity from arrest, criminal prosecution and civil lawsuits when they are posted overseas.

The police have registered a criminal case against six unnamed people, but have not yet filed charges.

Amnesty said it was petitioning Indian Prime Minister Narendra Modi for justice for the women, who were trafficked from remote villages in Nepal.

"Diplomatic immunity must not lead to impunity for human rights abuses," Gopika Bashi, women's rights campaigner at Amnesty International India, said in a statement.

"Authorities in India must promptly investigate the allegations, charge those suspected and seek their extradition from Saudi Arabia for prosecution, if required. The Saudi Arabian government, on its part, must not use the shield of diplomatic immunity to protect anyone, and must extradite suspects to India, if the need arises."

Related: Two Nepali maids alleging rape by Saudi diplomat return home