KARACHI -- A Pakistani judge on Saturday extended the police detention of four suspects in last month's car bomb attack on the U.S. Consulate in Karachi, which killed 12 people and injured 20.

A government official said the remand period was extended until august 3 during a brief appearance before an anti-terrorism court in karachi of the detained activists from al-almi, an offshoot of the radical harkat-ul-mujahideen organisation.

habib ahmed, assistant advocate general of southern sindh province, told reporters the extension was to allow police more time to complete an investigation and prepare an interim charge sheet.

earlier this month, pakistan's paramilitary rangers arrested three people, including two leading members of al-almi, on suspicion of involvement in the june 14 attack on the consulate in karachi's city centre.

all the victims in the fourth attack this year on a foreign target in pakistan were pakistanis.

the rangers detained the fourth suspect, mohammad ashraf, on wednesday night.

two of the accused -- mohammad imran and mohammad hanif, the head and deputy head of the organisation -- admitted at a news conference earlier this month their involvement in the consulate attack and a plot to assassinate president pervez musharraf.

they said they tried to kill musharraf late in april, but their car bomb failed to go off. they said their targets included u.s. interests in pakistan, such as fast food chains mcdonalds and kentucky fried chicken.

ahmed said mohammad ashraf confessed early on saturday to his alleged involvement in a plot to kill musharraf. the official declined to give further details.

harkat-ul-mujahideen has long been on a blacklist of organisations deemed "terrorist" by the united states and reportedly has links to muslim separatists fighting indian rule in kashmir.

pakistan's cooperation with the u.s.-led coalition pursuing osama bin laden, his al qaeda network and the taliban in afghanistan has angered islamic militants.