* Pakistan says needs death penalty to fight crime, militants
* New govt decides not to extend expired moratorium
* Rights groups say no link between crime and capital punishment
* Govt says 400 on death row, campaigners say 8,000 (Writes through with growing international condemnation)
Pakistan's new government, trying to appear determined to rein in escalating crime and militancy, has ended a ban on the death penalty, in a move condemned by international organisations as inhuman and retrograde.
Up to 8,000 people languish on death row in dozens of Pakistan's notoriously overcrowded and violent jails.
Once a moratorium is in place, reinstatement of capital punishment is rare, with more than 150 countries having already either abolished the death penalty or stopped administering it.
A 2008 moratorium imposed by Pakistan's previous government, praised at the time by global rights groups, expired on June 30.
"The present government does not plan to extend it," said Omar Hamid Khan, an interior ministry spokesman.
Pakistan's president must approve all executions. The government puts the number of people on death row at about 400. The method of execution is usually hanging.
"Pakistan is part of a dwindling minority of States who continue to retain the death penalty and carry out executions," the International Crisis Group said.
"The prospect of lifting the moratorium is all the more alarming given the extraordinarily high number of people on death row."
Khan said the new policy of Prime Minister Nawaz Sharif's government was to execute all death row prisoners, except those pardoned on humanitarian grounds.
There is, however, no firm evidence showing the practice can serve as a deterrent to crime or extremism, according to the United Nations and human rights groups.
"As long as the death penalty is in place, the risk of executing innocent people can never be eliminated," rights group Amnesty International said.
Pakistan says capital punishment is key to deterring crime in places such as Karachi, a megacity of 18 million plagued by violence, as well as in the areas on its border with Afghanistan where Taliban militants launch daily attacks.
Papua New Guinea, one of the world's poorest and most corrupt countries, reinstated the death penalty in May and repealed its sorcery laws after a string of gruesome "witch" killings and gang-rapes.
Asked about Amnesty's criticism, Khan pointed to the fact that capital punishment was still in use in parts of the United States, a nation he said was home to the "best judicial system".
Pakistan's moratorium drew praise because of concerns its courts and police were too inept to ensure the accused a fair trial. Pakistan did, however, break its own rules in 2012, when it executed a convicted murderer and a former army serviceman.
The previous government of the Pakistan's Peoples Party, whose former chairman, Benazir Bhutto, was a fierce opponent of capital punishment, enforced the moratorium soon after taking power in 2008 under President Asif Ali Zardari.
Zardari, the widower of Bhutto, who was assassinated in 2007, is due to step down later this year.