Shahid Nadeem Baloch, police deputy inspector general, said the dead woman worked for a relief agency.

A US embassy spokeswoman said that embassy personnel were hurt, but she was unable to say how many. A staff member from Britain's High Commission was also injured.

'Planted bomb'

Baloch ruled out any possibility it had been a suicide attack.

"There is a crater in the ground which suggests that it was a planted bomb, but we need to investigate further," he said.

He suggested a bomb could have been thrown over the wall.

"There are lots of injured people who have lost their limbs and legs"

Restaurant employee
No one immediately claimed responsibility for the attack.

A restaurant employee told one news agency: "There are lots of injured people who have lost their limbs and legs.

"It's a very bad situation. We don't know what has happened."

Al Jazeera's correspondent Kamal Hyder said the bomb blast was so loud that it was heard all over the neighbouring areas.

"It was planted at the back where the garden is situated. Behind the restaurant is a deserted lane," he said.

"In this city, there have been very rare attacks on public places. This has been an unprecedented attack because so far there has been no attack on restaurants."

More than 500 people have been killed in violence this year, including a number of suicide bombings.