The March 2 blast near the gates of the US consulate in the city of Karachi killed US diplomat David Foy, the bomber and three other people on the eve of a visit to Pakistan by US President George W Bush.
"The recent suicide attack on the US consulate in Karachi has been resolved and the culprits arrested," the interior ministry said on Friday in a statement quoting Pervez Musharraf, the Pakistani president, as telling a security meeting.
Musharraf did not say how many suspects had been arrested or identify them but a senior government official in Karachi said six people with links to al-Qaeda had been detained.
The official did not identify the six but said they had been arrested in the southern province of Sindh and the central province of Punjab, but did not say when.
"After DNA tests on the suicide bomber, we have also identified him," said the official, who declined to be named. He did not elaborate.
Security officials said the March blast was aimed at disrupting Bush's visit to Pakistan, but the US president went ahead with his trip to the capital, Islamabad, as scheduled.
US help sought
In another development, Pakistan has sought US help to capture an Arab al-Qaeda member who allegedly masterminded the foiled plot to blow up trans-Atlantic jetliners and operates out of Afghanistan's eastern mountains, where hundreds of American troops are based, a Pakistani intelligence official said on Friday.
Pakistani authorities have passed details regarding the al-Qaeda member to the American military, including his whereabouts in the remote Nuristan and Kunar provinces on the Pakistan border, through which hundreds of fighters and locals routinely cross, the official said.
The official, who spoke on condition of anonymity due to the sensitive nature of the investigation, declined to reveal the al-Qaeda operative's name or nationality.
He allegedly exchanged messages carried by a courier with detained British national Rashid Rauf, who is being interrogated by Pakistani authorities in connection with the plot that was smashed last week with at least 30 people arrested in both Britain and Pakistan, the official said.
The wanted al-Qaida operative is a close aide to Egyptian-born al-Qaeda No 2 Ayman al-Zawahiri, the official said.
Detained terror suspects have told interrogators that al-Zawahiri likely approved the plan to blow up passenger planes leaving London for the US by detonating disguised liquid explosives carried onboard in hand luggage.
A US military spokesman in Afghanistan said Pakistan routinely shares terror-related information with American counterparts, but he could not comment on whether Islamabad had notified US authorities about the al-Qaeda mastermind.