Police in Pakistan say a major attack on the country's biggest city has been prevented after three Pakistani militants blew themselves up when police raided their hideout.
The raid comes less than a week after a suicide truck bomber killed at least 60 people at the Marriott Hotel in Islamabad.
'We have saved Karachi from death and destruction. We know who they were and what was their target in Karachi, but we cannot disclose it immediately,' provincial police chief Babar Khattak told wire services.
The incident happened hours before Prime Minister Yousuf Raza Gilani was due in the city but there was no official indication that he was the target.
Police launched the raid in Karachi's Baldia neighbourhood based on information provided by an unidentified high value target who was arrested at dawn, Mr Khattak said.
'We surrounded the area after the detainee told interrogators that his colleagues hiding there were heavily armed and also carried suicide jackets,' Mr Khattak said.
The militants resisted the siege and lobbed at least five grenades at police, but caused no casualties.
'The militants blew themselves up after their ammunition was exhausted,' Mr Khattak added.
Mr Khattak said the militants were also wanted in connection with a suicide bombing at a religious gathering in Karachi in which 47 people were killed.
Exchange of fire over Afghan-Pakistani border
Separately, a US military official has said US and Pakistani troops have exchanged fire across the Afghanistan-Pakistan border.
US forces say two military helicopters operating in Afghanistan came under fire from a Pakistani checkpoint near the border between the two countries.
However, Pakistan's military say its soldiers fired warning shots at the helicopters after they intruded into Pakistani airspace.
No one was injured in the incident.
