Image caption The street was reportedly crowded with diners at the time

At least four people were killed and dozens injured when a bomb went off in a busy food street in Pakistan's eastern city of Lahore, officials say.

Local media said the explosion happened as people sat eating at restaurants in the Anarkali area on Saturday night.

At least 30 people were believed to have been wounded, with some in a critical condition. Children were reportedly among the casualties.

There was no immediate claim of responsibility.

The attack was the first of its kind for three years in Lahore, the capital of Pakistan's Punjab province and home city of newly elected Prime Minister Nawaz Sharif.

However, there has been a series of attacks around the country since Mr Sharif was sworn in last month - blamed on Islamist groups including the Pakistan Taliban - which have left more than 150 people dead.

'Chaos everywhere'

The bomb was placed in an outdoor eating area in the old part of Lahore and detonated at a particularly busy part of the evening.

Pictures taken shortly after the explosion show broken chairs and tables lying on the ground.

Eyewitnesses reported seeing windowpanes smashed and furniture from the food stalls destroyed.

"The blast site is just few metres away and the blast was so loud that I was stunned for a while," shopkeeper Naseed Ahmed told Reuters.

"There was chaos everywhere."

Local resident Mohammad Anwer said more should be done to protect people.

"This happened on the weekend when there is huge crowd gathered here," he told Reuters news agency.

"The government should do something about these kinds of incidents. People feel very insecure."

Police official Zulfiqar Hameed said the bomb was connected to a deep freezer in one of the restaurants, according to the news agency.

Mr Sharif has called on the leaders of all major political parties to meet on Friday to discuss initial ideas for a new security strategy to tackle the growing threat posed by militants.

But the BBC's Richard Galpin in the capital Islamabad says it could be months before any plan comes into effect.