Security has been ramped up at churches across Pakistan where tensions are still simmering over the recent acquittal of Christian woman Asia Bibi.

Churches have previously been the target of suicide bombers and this year, police have trained hundreds of Christian volunteers in an effort to see the season through peacefully. 

More than 1,500 police have been deployed across Islamabad and Rawalpindi to protect churchgoers over Christmas, AFP news agency reports.  CCTV cameras have also been installed at entry points and parking restrictions have been put in place to keep cars at least 100m away from church buildings.

In Abbottabad, a district north-east of Islamabad, police were sweeping churches with sniffer dogs and bomb disposal units ahead of Christmas celebrations.

Christians have been fearful of retaliatory attacks since Bibi was acquitted of blasphemy, for which she had received a death sentence.  She was freed from prison in November but immediately forced into hiding as Muslim extremists hunted her down.

'We're afraid,' Pastor Munawar Inayat at Holy of Holies Church in Islamabad told Samaa TV. 'We can't speak against anyone.'

A petition review against Bibi's acquittal has been filed with the Supreme Court, casting a shadow over her first Christmas with her family after eight years on death row.  A hearing for the petition review has been set for January. 

Wilson Chowdhry, chairman of the British Pakistani Christian Alliance, said Bibi would be spending Christmas with her husband in a secret location under police protection. 

'Despite her joy at being free I cannot believe that Asia Bibi is feeling like much of a winner today,' said Chowdhry.

He added: 'Christmas will be a lonely time for Asia Bibi and her husband Ashiq as they spend it together away from other family members as we know the appeal will not be heard before Christmas and is expected during the early part of the new year.'

Analyst Fasi Zaka told AFP that the longer Bibi remains in limbo, the greater the danger for her and for other Christians.

'For some elements if they don't have access to Asia Bibi they'll find stand-ins for their vengeance,' he told the news agency.

Britain has faced strong criticism for so far refusing to offer asylum to Bibi, despite appeals from her family.  Prime Minister Theresa May and Home Secretary Sajid Javid have said they are working with other countries on a solution. 

May has denied speculation in the media that she was concerned about tensions among Muslims at home if Britain offers asylum. 

Last week, the British Government was accused of funding death-sentence courts in Pakistan. The Guardian reports that while the Foreign Office has invested millions, legal charity Reprieve says that the courts do not meet international standards.

Harriet McCulloch, the deputy director of Reprieve, said: 'It is deeply troubling that Britain is assisting in the investigation and prosecution of crimes that carry the death penalty in Pakistan, particularly as those crimes are being tried in courts that do not uphold basic standards of due process and where the rates of wrongful conviction are alarmingly high.

'In the last three years, British taxpayers have spent £10m supporting a legal system that convicts and sentences people to death for alleged crimes that often have nothing to do with terrorism.'