India never agreed to accept the return of any of the 157 Tamil asylum seekers who were not Indian citizens, a spokesman for the Indian high commission has said.

Tarun Kumar, information officer at the high commission, said India had agreed only to “investigate” the situation of non-citizens.

The immigration minister, Scott Morrison, said he had struck a “highly unusual” agreement with the Indian government under which asylum seekers – most of whom were Sri Lankans who had been living in India – would be able to return to India after discussions with Indian consular officials.

Morrison said the agreement had never been effective because the asylum seekers, who had been transferred to the Curtin detention centre in Western Australia after spending weeks at sea in an Australian customs vessel, had refused contact with the Indian officials. Because of this, Australia made the decision late last week to send the asylum seekers to Nauru for processing.

“We had actually come up with what was in effect a humanitarian plan to get people who had been living in India, and about two-thirds of them on that vessel had been living in India,” Morrison said over the weekend.

“It is disappointing that despite the government’s best efforts working closely with the government of India, who we greatly appreciate the cooperation of, that people who had the opportunity to talk to Indian consular officials and have the opportunity to be returned to India where the majority of those who were on that vessel had been living prior to coming on that boat; they had the opportunity to return there and pursue that with Indian consular officials as part of a very unusual and unique arrangement that we were able to achieve last week when I was in New Delhi.”

Kumar said Indian consular officials had never made it to Curtin and had had no communication with the asylum seekers.

“The Indian government had agreed to take back Indian citizens. Regarding non-Indian citizens … there was no agreement to take them back. We had agreed only to investigate the matter,” he said.

Asked whether the return of non-citizens had therefore been at the very least a possibility, Kumar said: “I can’t say that. The only commitment was that we would investigate them.”

On 26 July, India issued a statement saying there had been “some press reports on briefings by Australian minister of immigration and border protection Scott Morrison on the issue of 157 persons who are held up at sea off the shores of Australia and his interactions with the Indian minister for home affairs and the minister for external affairs n 23 July 2014.”

“India has a policy of not supporting illegal migration either into India or anywhere outside India. During the visit of Minister Morrison to India, the Indian authorities have clearly conveyed to the Australian side that the first requirement is to provide consular access to Indian high commission officials in Australia to the persons. India’s policy is to accept return of Indian citizens and other persons whose return it is obligated to accept under applicable Indian domestic law. As per current policy, India will take back its own nationals provided the consular access clearly determines their origin,” the statement said.

Morrison said the decision to refuse contact with Indian consular officials meant the asylum seekers “who were previously living in India will now be unable to take advantage of the humanitarian offer being made by the Indian government, secured by my visit to New Delhi last week, that would have potentially enabled their return to India.”