The governor of Pakistan's Punjab province, Salman Taseer, has died after being shot today by a gunman in the country's capital, Islamabad.
Mr Taseer was killed by one of his guards over his opposition to Pakistan's controversial blasphemy law, Interior Minister Rehman Malik said.
Rights groups say the law is often exploited by religious extremists as well as ordinary Pakistanis to settle personal scores. Islamist groups have been angry over what they believe were government plans to change or abolish the law.
The killing came as Pakistan's prime minister Yusuf Raza Gilani tried to muster support for the government after a main coalition partner quit over government fuel price policies.
A witness at the scene said Mr Taseer was stepping out of his car at a shopping area when he was shot.
"The governor fell down and the man who fired at him threw down his gun and raised both hands," said the witness, Ali Imran.
Mr Malik said the slain politician's guard, identified as Malik Mumtaz Hussain Qadri, confessed and had been arrested but investigations would determine if others were involved.
The shooting left blood stains on a parking area on the edge of the Kohsar shopping centre, which is popular among foreigners in Islamabad.
Mr Taseer, a liberal and charismatic politician close to President Asif Ali Zardari, had no role in day-to-day central government but his killing will compound a sense of crisis and reinforce the impression that the government is nowhere near to stabilising the country.
The blasphemy law came under the spotlight after a court sentenced a Christian mother of four, Asia Bibi, to death in a case stemming from a village dispute.
The law enjoys widespread support in Pakistan, which is more than 95 per cent Muslim, and most politicians are loathe to be seen as soft on the defence of Islam.
But Mr Taseer had visited Ms Bibi in prison in a campaign for her release.
"I was under huge pressure sure 2 cow down b4 rightist pressure on blasphemy. Refused. Even if I'm the last man standing," Mr Taseer wrote on his Twitter page last Friday.
Analysts said Mr Taseer's death would compound political tension as the opposition closes in on the government.
The second-biggest opposition party also said it would not push for a no-confidence vote, suggesting the opposition may prefer to wear down a weak prime minister by blocking legislation or staging protests to force an early election.
Even before the latest political turmoil, the government faced opposition from almost all political parties to its bid to implement a new sales tax - a key condition of the IMF for the release of the sixth tranche of the loan.
The tax had originally been scheduled for implementation in July but has been delayed several times. It is under review in parliament.
The delay will squeeze Pakistan's budget as its spending is surging to deal with the aftermath of floods last year that caused almost $10 billion in damage. Endemic tax evasion means the country's tax-to-gross domestic product ratio is about 10 per cent, one of the lowest in the world.
Pakistani Taliban militants may also seize on Mr Gilani's vulnerability by stepping up its violent campaign of suicide bombings to destabilise the government.
The upheaval coincides with increased US pressure on Pakistan to hunt down militant groups to help it turn around the faltering war in Afghanistan.
Reuters