India has complained to Canada after several officials linked with its security establishment were denied visas, officials in New Delhi said on Thursday.
The visa rejections, on grounds of human rights records, came to light just weeks before Indian Prime Minister Manmohan Singh is to travel to Toronto for a G20 meeting.
Indian officials said about six serving and retired officials linked to the intelligence agency and security forces were denied visas over the past 18 months.
"The matter has caused concern and it has been appropriately taken up with the Canadian officials," said an Indian government official, who asked to remain anonymous.
Some reports said Canada's high commissioner had been summoned this week by the Indian foreign ministry but neither side would confirm that had occurred.
Visa requests were turned down because the applicants either worked for India's internal intelligence agency or for the army in the disputed, heavily militarized region of Kashmir.
Indian forces in Kashmir fighting a 20-year-old separatist insurgency have sometimes been accused of violating human rights, a charge the government denies.
Canada's foreign affairs ministry has sought to douse the row, saying it was "reviewing the situation."
"Due to privacy reasons we can not comment further," Catherine Loubier, the ministry's director of communications, said in a statement issued earlier in the week in Ottawa.
Indian media reported this week that one of the applicants, a former guard with India's Border Security Force (BSF), was denied a visa on the grounds that his organization was a "notoriously violent" unit which engaged in "systematic torture."
The case prompted several other serving and former Indian security and military officials to come forward to say that their visa applications had also been rejected with "offensive remarks."