Khadija Shah, a 25-year-old pregnant British woman, could be sentenced to death in Pakistan after she was caught attempting to smuggle heroin worth £3.2million.

The mother of two was returning to her home in Birmingham when she was arrested by police officers who uncovered 140lb of the drug concealed inside clothes in three suitcases, the Daily Mail reported.

Shah, who was visiting relatives in Pakistan for over a month, told authorities in the capital city of Islamabad that she had taken the bags as a favour for strangers she met in the city.

She said: “This morning when I was coming out of the guest house to leave for the airport, someone came to the guest house and requested me to carry his bags along with me and hand them over to his relative in Birmingham. I had no idea what was inside.”

Authorities said Shah was acting suspiciously, which is why they checked the bags.

“Her movements compelled us to check the luggage properly,” said one.

“The three bags were apparently filled with household goods and clothes. When properly checked, contraband was recovered.”

The Daily Mail reported that the haul is said to be the biggest of the Class A drug ever recovered at Islamabad airport. Under the nation’s law, anyone arrested with drugs weighing more than 22lb (10kg) faces at least life imprisonment and at most the death penalty.

Shah’s boyfriend, Amar Ali, the father of her unborn child, plans to travel to Pakistan to pick up her children, both from a previous relationship.

He claimed he had spoken to his girlfriend shortly before she left for the airport and had warned her against helping the strange men transport their bags back to the UK.

At Miss Shah’s home yesterday, Mr Ali said: “She was supposed to be coming home today.

“I spoke to her on the phone but got cut off. I told her not to do that. I told her to trust no one.

“When I was there recently everyone there wants to be your friend because you’re from England. People try to get you to take bags to the UK for them.

“I said, ‘Make sure you don’t take any luggage for anyone’.”

Shah, who spoke to Ali while in custody, told him that she had been beaten up by police and was concerned for the safety of her children.