Amina Lawal, 30, was found guilty by a court in Katsina state in March after bearing a child outside marriage.

This judgement will be carried out as soon as your baby is weaned

Judge Aliyu Abdullahi

The BBC's Dan Isaacs, reporting from the court in Funtua, northern Nigeria, says that the court's ruling can only serve to heighten tensions between Christians and Muslims in Nigeria.

The introduction of Islamic holy law - or Sharia - in northern Nigeria's mostly Muslim states in the past two years has sparked violence in which hundreds of people have been killed.

Our correspondent says Monday's ruling has come as a surprise and human rights groups have promised to take the case to a higher court.

They have 30 days to lodge an appeal.

This case could now end up in the supreme court in Abuja, where central government has declared such harsh Sharia judgement unconstitutional.

Tears

The largely-male crowd in the courtroom reacted to the judgement of judge Aliyu Abdullahi with shouts of "Allahu Akbar" (God is great).

"We uphold your conviction of death by stoning as prescribed by the Sharia. This judgement will be carried out as soon as your baby is weaned," the judge said, as Amina cradled her eight-month-old daughter Wasila, reports the French news agency, AFP.

She was led away in tears, according to AFP.

Women's rights groups say Sharia is harsh for women

"I'm not happy at all. We thought they were going to discharge her," said Clara Obazele, a spokeswoman for Aisha Ismail, the federal government's minister for women's affairs.

"We're going to appeal the judgement."

No one has yet been stoned to death for adultery in Nigeria.

A woman convicted under very similar circumstances last year won her appeal a few months ago.

Several thieves have however had their hands amputated.

Supporters of Sharia say they will not be deflected from upholding laws they see as the will of God.