Massive suicide bombs ripped through a seven-story police headquarters and a house in Lahore on Tuesday, killing at least 20 people and wounding more than 150, deepening Pakistan's security crisis as a wave of Islamic militancy sweeps the country.

The two blasts happened about 15 minutes apart in different districts of this eastern city. The first tore the facade from the Federal Investigation Agency building as staff were beginning their work day. It also damaged scores of homes in the neighborhood.

City police chief Malik Mohammed Iqbal said an explosive-packed car was driven into a parking lot and detonated next to the building _ which houses a department of the federal police's anti-terrorism unit _ knocking out the walls of several offices and part of a stairwell.

Pervez Malik, another city police official, said 17 people were killed and another 165 were wounded.

"It is the deadliest attack I ever saw," Iqbal said.

The second explosion shattered the office of an advertising agency in a residential neighborhood, about 15 miles away. Mohammed Afzal, another city police official, said three people were killed there, including two children of a gardener.

Iqbal said both blasts were suicide attacks.

The blasts come amid a spate of violence that authorities are blaming on Taliban and al-Qaida-linked militants, spreading beyond their strongholds along the Afghan border, and as the victors of last month's elections prepare to form a new government.

The party of Nawaz Sharif, which is set to be the junior partner in the incoming coalition, blamed military operations ordered by U.S.-backed President Pervez Musharraf for destabilizing the country and called for him to resign.

"He has carried out indiscriminate operations in the tribal areas that have opened up new fault lines in Pakistani society," party spokesman Ahsan Iqbal said.

Musharraf condemned the "savage" bombings and said they "cannot deter" the government's resolve to fight the scourge of terrorism "with full force," according to a statement carried by the state-run Associated Press of Pakistan.

Footage from private television networks shot shortly after the first blast showed flames still leaping from the tangle of bricks, wrecked vehicles and even a fallen tree next to the police building, located near a key city center intersection.

Paramedics carried a bloodied body on a stretcher from the building, while volunteers sifted through the rubble with bare hands, apparently searching for survivors.

Scores of nearby houses sustained major damage. Gates and doors were torn off, windows blown in and air conditioners dislodged and left in the street.

"It was like hell let loose on us," said homeowner Fazal Muqeem, 42. Three of his family members were slightly hurt by fallen crockery and broken glass.

Uzair Ahmed, a watchman guarding a bungalow, said he heard a deafening boom and something hit him in the head and face.

"I rushed out in panic. ... Everybody was running and crying. Smoke was all around and that was it. I only came to my senses in the hospital," Ahmed, his head bandaged, said from his hospital bed.

The second attack hit an advertising agency at a house in the upscale Model Town neighborhood.

Salman Batalwi, chief executive of the SB&B agency, told Dawn News television that the house had been "completely blown up" and several members of staff seriously wounded and the children of a gardener had been killed.

Batalwi told Dawn News a house rented by the party of slain opposition leader Benazir Bhutto and used by her widower was nearby, but had no idea who had been the intended target.

Dawn quoted police officer Asmal Gondal as saying that two suicide bombers had driven a pickup truck up to the house, brushed aside guards posted at the gate and detonated their explosives.

Until recently, Lahore, Pakistan's cultural capital, had been spared the suicide attacks that have struck all other major cities in the past year.

But now it has suffered three attacks within two months. On Jan. 10, a militant walked into a crowd of police guarding a courthouse and blew himself up, killing 24. A double suicide attack in Lahore killed four people at a navy training college last week.

Tuesday's attack was the first major act of terrorism since Sharif's and Bhutto's parties announced over the weekend that they would form a coalition government after routing Musharraf's allies in the Feb. 18 parliamentary elections.

The parties are vowing to restore judges axed by Musharraf to secure his own re-election last year _ setting them on a collision course with a key U.S. ally in its war on terror.

Asif Ali Zardari, Bhutto's widower, however, sought on Sunday to assure the West that the new government would renew Pakistan's commitment to countering Taliban and al-Qaida militants _ a seemingly different stance to Sharif.

Also Tuesday, Australia announced it was postponing its international cricket tour to Pakistan, which had been scheduled for later this month, due to security concerns.

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Associated Press writers Munir Ahmad and Sadaqat Jan in Islamabad contributed to this report.