A Roman Catholic cardinal has accused the UK government of operating an "anti-Christian foreign policy".
Cardinal Keith O'Brien has attacked plans to increase aid to Pakistan to more than £445m, without any commitment to religious freedom for Christians.
Speaking in Glasgow, Cardinal O'Brien called on Foreign Secretary William Hague to seek human rights guarantees.
The Foreign Office said it raised concerns and lobbied governments about persecution wherever it arose.
The cardinal's call came as a report by Vatican-approved agency Aid to the Church in Need suggested 75% of religious persecution around the world was directed against Christians, affecting 100 million people.
The church highlighted the assassination of Pakistani minority affairs minister Shahbaz Bhatti at the start of March.
Mr Bhatti was the only Christian member of the cabinet in Pakistan.
Cardinal O'Brien said: "I urge William Hague to obtain guarantees from foreign governments before they are given aid.
"To increase aid to the Pakistan government when religious freedom is not upheld and those who speak up for religious freedom are gunned down is tantamount to an anti-Christian foreign policy.
"Pressure should now be put on the government of Pakistan - and the governments of the Arab world as well - to ensure that religious freedom is upheld, the provision of aid must require a commitment to human rights."
He said the report's estimate of persecution against Christians was "intolerable and unacceptable".
"We ask that the religious freedoms we enjoy to practise our faith, will soon be extended to every part of the world and that the tolerance we show to other faiths in our midst will be reciprocated everywhere," he added.
Foreign Office Minister Alistair Burt said: "Freedom of religion is a fundamental human right and we condemn and deplore religious persecution in any form.
"The effective promotion of human rights, including freedom of religion, is at the heart of our foreign policy."
He said Britain raised concerns and lobbied governments about religious freedom and persecution wherever it occurred, including in Pakistan.
"It is vital that Pakistan guarantees the rights of all its citizens, regardless of their faith or ethnicity," he added.
"We will continue to press for religious freedoms to be upheld in Pakistan and around the world."
The report also highlighted the Christian population of Iraq, which it says has gone from an estimated 1.4 million to as low as 150,000 over the past 25 years.
Archbishop Bashar Warda of Erbil, in Iraq, said: "The Persecuted and Forgotten report and the work of Aid to Church in Need are critical to us as members of the worldwide Christian community.
"This information will significantly contribute to building international support and solidarity for Christians around the world where our human rights and our religious freedom have been stripped away."