Open Doors, which serves persecuted Christians around the world, has called on the forthcoming Commonwealth Heads of Government meeting to put freedom of religion and belief at the heart of their discussions.

Set to take place in London and Windsor next week, it is seen as particularly significant for the UK, which wants to strengthen its ties with the Commonwealth ­ – made up of 53 countries, mainly former territories of the British Empire – following the decision to leave the European Union. Some have poor records on religious freedom.

Open Doors' head of advocacy, Zoe Smith, said: 'The Commonwealth Heads of Government Meeting will be unable to realise its agenda of securing a common future without explicitly including the right to freedom of religion or belief in its plans.

'We urge leaders of the Commonwealth to ensure that this fundamental human right is placed at the heart of discussions in London and that decisive measures are taken to ensure it is protected across all Commonwealth countries.'

Eight of the 53 Commonwealth countries appear on the Open Doors World Watch List – the ranking of the 50 countries where it is most difficult to be a Christian.

Among them are Pakistan at number five, where Asia Bibi has been in prison since 2009 for drinking from the same cup as her Muslim co-workers in a rural field. Schoolboy Sharoon Masih was killed for drinking from a water bottle that was passed around the classroom.

At number 11, its neighbour India also features. According to Open Doors, 'As the Hindu nationalist agenda increasingly takes over in India, Christians are facing rising levels of persecution.' It cites sisters Meena (32) and Sunita (25), believers from a Hindu background, who were left to die after villagers attacked them for being Christians.

The other Commonwealth countries featured are Nigeria, Malaysia, Brunei, Kenya, Bangladesh and Sri Lanka.