At least 12 children were killed on Saturday in a bomb explosion in northwest Pakistan, officials said. "The children had found the bomb outside a girls' primary school in Luqman Banda village of Lower Dir town," local police official Said Zaman told AFP.
Officials had earlier said at least four children died in the blast. The children killed included seven boys and five girls ranging between five and 13 years old, said Zaman, who visited the site of the blast in the remote mountainous village.
He said that "the bomb was of oval shape and it exploded while children were playing with it in the compound of their house not knowing that it was an explosive device".
Four others including a woman were wounded in the blast, he said, adding that an investigation had been launched to ascertain what kind of bomb it was and how the children got hold of it.
Another local police official Sultan Mehmood also confirmed the incident and the death toll. Prime Minister Yousuf Raza Gilani "expressed grief and sorrow over the loss of innocent lives of children in the explosion," an official statement said.
"Those playing with the innocent lives would not escape the wrath of Allah and law of the land," it quoted him as saying.
The prime minister also directed law enforcement agencies to closely monitor the "miscreants" trying to create a "law and order situation in the country".
Pakistan's northwest has been wracked by violence since hundreds of extremists fled across the border to escape the US-led invasion of Afghanistan in late 2001.
Lower Dir is part of the Malakand area, where President Asif Ali Zardari has authorised an agreement allowing the enforcement of sharia law in exchange for the end of a brutal two-year-long Taliban uprising concentrated in Swat.
The rugged mountainous town is located 75 kilometres (46 miles) west of Swat, a former ski resort and erstwhile jewel in the crown of Pakistan's tourism industry, which is now under the control of radical Islamists.
A number of girls schools were targeted during the uprising by militants, who believe it un-Islamic for women to be educated.
The beheading of opponents was common and brutal punishments, such as floggings, were often carried out in public, as the radical Islamists sought to impose their brand of strict sharia in the region.
Saturday's explosion coincided with the withdrawal of scores of Taliban militants from Buner district, 100 kilometres northwest of the capital Islamabad, after their earlier overrunning of the area sparked international concerns and led to US warnings that Islamist advances pose "an existential threat" to nuclear-armed Pakistan.