A total of seven small blasts left 43 people wounded in Pakistan's commercial capital of Karachi, officials confirmed Tuesday, as investigators probed the previous evening's chaos.

Pakistani President Pervez Musharraf urged national unity, and security forces were on high alert. Monday's string of explosions followed a weekend suicide blast in the capital, Islamabad, that killed 18 people, most of them police.

Karachi police chief Wasim Ahmed confirmed that at least eight men have been detained so far and that some explosives were recovered in overnight raids. Zulifqar Mirza, the provincial interior minister, told reporters that seven devices were used.

The 43 people wounded were all in stable condition, said Mirza, adding that the motive behind the attacks appeared to be creating chaos in a city where political, ethnic and religious violence is common.

Mirza ruled out the possibility of Pakistani Taliban leader Baitullah Mehsud being involved. "We have found concrete evidence about the culprits, but for now I cannot disclose it," he said.

Blasts within an hour of each other

Musharraf termed the Karachi attacks a conspiracy aimed at destabilizing Pakistan.

He said in comments late Monday carried by state media that Pakistan was fighting terror in its own interest. Many Pakistanis blame the unpopular president's alliance with the U.S. in fighting terror for fuelling violence in their country.

The Karachi blasts came within about an hour of each other, spawning a wave of fear in residential and commercial spots in the crowded port city.

Karachi, the provincial capital of southern Sindh province, is where former prime minister Benazir Bhutto narrowly escaped a suicide attack in October that killed 140 people at a rally of thousands of her supporters. Bhutto was later slain in a December attack in Rawalpindi.

Investigations also continued into the Islamabad attack.

On Monday evening, federal Interior Ministry chief Rehman Malik said authorities had found a severed head, possibly the attacker's, whose damaged face was being reconstructed by a plastic surgeon so police could release a sketch to the public.