Police in India are using the pretext of violence from Hindu militants to ban Christmas services in Christian venues, according to Release International.
In the south-western state of Karnataka, police have clamped down on Christmas meeting in churches, halls and homes.
In the city of Belguam (also known as Belgavi) in the north of the state, police are said to be preventing Christians from meeting.
Release partner on the ground, Archbishop Joseph D'souza, Moderator of the Good Shepherd Church of India, said the situation in Karnataka was "tense".
"In Belguam police are not allowing Christian groups to meet in local churches, house groups and halls. This situation will mean the inability to have Christmas services," he said.
Hindu extremists have "crossed a red line by walking into Christian worship and conducting their own services", but the authorities do nothing to stop them, the Archbishop continued.
"We have not seen anything like this before. They are interrupting Christian services with their Hindu chants. And these extremists are not being arrested," he added.
In order to pressure state authorities to outlaw religious conversion altogether, Hindu militants are accusing Christians of practising forced conversions, Release reports.
Karnataka is the latest Indian state poised to pass new legislation to make it much more difficult for Hindus to convert to Christianity.
Archbishop D'souza said: "Some Hindu leaders accuse Christians of conducting forced conversions. But the very idea of forced conversions is anathema to Indian Christians.
"In many parts of the nation, Christians are now afraid because of the way the extremists are taking the law into their hands."
He is calling on India's Prime Minister Narendra Modi to intervene to safeguard Christians over Christmas.
"There is no place in India's democracy for incessant campaigns of hatred aimed squarely at the Christian community, its churches, NGOs and schools. We expect protection from the Prime Minister," the Archbishop said.
Christians in Pakistan are also facing a challenging Christmas.
Release International reports that police there have started to seal off some Christian areas supposedly to protect the Christian communities from terrorist attacks.
Release partner Waseem Khokhar said: "To get in, everyone has to show their ID card. Security is a big, big issue.
"Half the family will go to the midnight service, and the other half will go to the main service, because they don't all want to die. If, God forbid, something happened, then at least one person would be left to look after their children."
Paul Robinson, the CEO of Release International, is asking Christians in the UK to stand with their persecuted brothers and sisters in prayer.
"Release calls on India and Pakistan to step up security to allow Christians to celebrate Christmas in peace," he said.