Two devices planted 30 metres (yards) apart exploded within seconds of each other at the bustling Moon Market area in central Lahore as people milled around the shops and restaurants, engulfing the area in flames.
"A total of 49 people were killed and around 150 were injured in these blasts," Chaudhry Shafiq, a senior city police official, told AFP.
Police officials said that the bombs were remotely-detonated and set scores of shops and buildings ablaze. Firefighters and rescue staff worked into the night to quell the flames and free people trapped under the rubble.
Attacks blamed on Islamist fighters have surged this year as Pakistani troops battle the Taliban in the rugged tribal regions near the Afghan border, under fierce US pressure to do more to destroy extremist strongholds.
Rana Sanaullah, provincial law and home minister for Punjab province, told reporters late Monday that the strikes were planned as revenge for an ambitious military operation to dismantle Taliban strongholds in South Waziristan.
"After the successful operation in Waziristan, the terrorists have started targeting innocent people, women and children," he said.
Opposition politician Shahbaz Sharif, who is chief minister for Punjab province, visited some of the blast victims in hospital, and also blamed militants for the attack in the city of eight million people.
"A militant group is targeting the innocent people, they want to terrify the people but I can assure the nation that we will soon win this war," he told reporters outside the hospital.
"This is a national challenge, but the nation will soon see the day when there will be peace in this country."
Lahore was the second provincial capital to be targeted Monday, after a suicide bomber killed 10 people outside a court in the northwest city of Peshawar at around midday in the latest strike on the troubled city.
Pakistan´s military is engaged in offensives against Islamist fighters across much of the northwest including the tribal areas bordering Afghanistan, enraging militants holed up in the rugged mountains.
October and early November saw a fierce surge in attacks, including a huge suicide car bombing on October 28 in a Peshawar market that killed 125 people in the worst attack in Pakistan in two years.
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