Religious freedom in Vietnam is under threat from a new law on belief and religion, according to a joint statement from a number of faith groups.

27 organisations have signed a statement urging the Vietnamese government to revise the draft law which currently places "severe limitations" on religious freedom, according to Christian Solidarity Worldwide (CSW).

"The provisions of the draft law, is passed, would act as a powerful instrument of control placing sweeping overly broad limitations on the practice of religion or belief within Vietnam, perpetuating the already repressive situation," the statement read.

It goes on to highlight concerns about the draft law such as the onerous requirements for registering religious organisations and excessive state control over the internal affairs of religious groups.

CSW said these restrictions are incompatible with the International Covenant on Civil and Political Rights (ICCPR), to which Vietnam is a party.

The law would empower the government to intrusively monitor religious organisations and, because of its broad and ambiguous language, could be used as a basis for discrimination against minority groups, the group warned.

"We join with civil society and religious organisations in Vietnam and around the world in calling on the Vietnamese government to revise the draft law in line with international standards on the right to freedom of religion or belief, in accordance with Article 18 of the ICCPR," said Christian Solidarity Worldwide.

Vietnam's record on religious freedom is already poor, according to a 2014 UN report.

"Autonomy and activities of independent religious or belief communities...remain restricted and unsafe," said Dr Heiner Bielefeldt, the UN special rapporteur on freedom of religion or belief.

"The rights to freedom of such communities are grossly violated in the face of constant surveillance, intimidation, harassment and persecution," his report read.

The statement, signed by many other human rights organisations such as Amnesty International, urged the government to revise the law so it was consistent with Vietnam's commitment to the ICCPR.