Hundreds of single mothers and rights activists demonstrated outside Nepal's parliament building on Thursday, urging members of a special assembly drafting a new constitution not to weaken the citizenship rights of young Nepalis.

One activist said a law being considered, that would give citizenship only to children of two Nepali parents, would strip some one million young people of Nepali citizenship - on top of about 4.3 million who already have no identity documents.

Housewife Usha Chhetri remembers the day when her husband left their home in the capital Kathmandu to visit his parents in a village in the remote eastern district of Bhojpur.

Twenty years on, he has not returned - leaving 45-year-old Chhetri struggling not only to bring up their three children, but also to get them official recognition and their rights as Nepali citizens.

"My children are crying at not being able to get (identity) cards. They are like aliens in their own land despite being born in Nepal," said Chhetri. Without proof that her estranged husband is Nepali, her children have a bleak future, she said.

Her 26-year-old son cannot get a passport to go to the Middle East for work as millions of Nepalis do, and her other son had to abandon plans to become an engineer because the college would not admit him without identity papers.

Despite a 2006 law allowing single parents to pass on their citizenship to their children, few women have been able to do so, largely because bureaucrats arbitrarily refuse to approve nationality applications for the children of single mothers.

Activists say the position may worsen for children brought up by single mothers, as the Himalayan nation is mulling more stringent citizenship laws in its new constitution.

A specially elected assembly charged with preparing the young republic’s new constitution is considering a law which would allow only children who have two Nepali parents to be recognised as citizens.

Activists say that as mothers generally bring up the children after a relationship ends, the law would hit single mothers hardest, as they tried to prove their estranged husbands were Nepali.

"This means all children of single mothers will not be able to get citizenship certificates and they will become stateless," said Subin Mulmi of the Forum for Women, Law and Development.

Mulmi said an estimated 4.3 million people in Nepal – most of them children of single mothers - had no citizenship card, and if the new law comes into force an additional one million would become stateless, large numbers in a population of around 28 million.

Identity cards are needed for everything from college admissions and job applications to getting a driving license and opening a bank account.

"Mothers should not be deprived of this right in the new constitution," said protester Rosa Paudel, who has struggled for years to get an identity card in the absence of her father, who left her mother when she was a child.

Government officials said no decision on the proposed new law had been made yet.

"This subject is under discussion at the Constituent Assembly and its members are competent to make a proper decision," Tek Prasad Dhungana, spokesman of the Ministry of Law and Justice, told the Thomson Reuters Foundation.

Nepal, located between China and India, is still recovering from a decade-long civil war which ended in 2006.

The new constitution, made necessary by the end of the monarchy in 2008, is due to be passed on Jan. 22 but parliamentarians are not expected to meet the deadline.