A search has resumed for a baby believed to have fallen from a ferry in Northern Ireland.

Eyewitnesses said the child was with a woman who plunged from the Stena Line boat as it made its way into Belfast port from Cairnryan on Scotland's western coast last night.

The sea search for the infant restarted this morning in poor weather conditions.

The woman was rescued and taken to the Royal Victoria Hospital in Belfast for treatment, where she is stable. She was recovered by a pilot boat 15 minutes after the alarm was raised.

The incident happened in Belfast Lough, close to Holywood, Co Down, at around 6.10pm on a busy shipping route for passengers and freight between Northern Ireland and Scotland.

John McPoland, a spokesman for the Northern Ireland Ambulance Service, said two ambulance crews treated her.

"She had been in the water for a while so you can understand that with the coldness of the water she would have been hypothermic," he said.

Agencies, including the police helicopter, the Irish Coastguard and the RNLI have been involved in the search for the baby.

Police Service of Northern Ireland officers boarded the ferry, which is docked in Belfast Port.

A PSNI spokesman said: "It was reported that two people fell into the water from a ferry. One person was rescued and was taken to hospital for treatment for suspected hypothermia.

"The search operation is ongoing for the second person, this is believed to be a young child."

All Stena Line sailings to and from Belfast were cancelled last night and Belfast Port was closed.