Islamabad (PTI): A powerful bomb blast rocked an upmarket restaurant in the heart of the Pakistani capital on Saturday, killing a Turkish woman who worked in the US embassy here and injuring 15 people, most of them Americans.

The blast, which occurred at 8.40 pm in the lawn outside the Luna Caprese restaurant in the bustling Super Market, sent plumes of smoke in the air and created a crater at the site.

A sizeable number of citizens of Western nations, including several employees of the US embassy, were present in the restaurant at the time of the explosion.

Pakistani officials said a Turkish woman, who worked as a nurse in the US embassy, was killed in the attack. Earlier reports had identified the deceased as an American.

Among the injured were seven US citizens, a Chinese national, a Briton, a Canadian citizen, two Japanese journalists and three Pakistanis.

US embassy spokesperson Kay Mayfield said personnel from the mission were among the injured.

Interior Secretary Syed Kamal Shah ruled out the possibility of the blast being caused by a suicide bomber.

Police officials said the blast was carried out with an explosive device that was apparently planted in the lawn outside the restaurant. The explosion shattered the restaurant's widows and many of the injured were hit by shards of glass.

Several senior Pakistani bureaucrats and diplomats of various countries, including the Indian High Commissioner, live in neighbourhoods near Super Market.

Shah visited the site of the blast, which was also inspected by a bomb disposal squad and forensic experts of the Federal Investigation Agency.

The blast came a day after authorities stepped up security across Islamabad ahead of the first session of the new National Assembly on March 17.

Security agencies had sounded an alert regarding possible suicide attacks in the federal capital.

Asked if today's attack was the result of a security lapse, Interior Secretary Shah said: "Such (attacks) in markets and open places can happen anywhere, and not only in Pakistan. I can assure you that we will do our best, we are seized of the security situation."