The United Nation's refugee agency (UNHCR) says the Abbott government's policy of towing or turning back boats may breach Australia's obligations under international law.
UNHCR spokesperson Babar Baloch says the organisation is seeking an explanation from the Australian government over reports a number of asylum-seeker boats have been returned to Indonesian waters.
Mr Baloch said the UNHCR found a policy of "pushing" back asylum-seeker boats "very concerning".
"Any such approach would raise significant issues and potentially could place Australia in breach of its obligations under the Refugee Convention and international law," he told ABC radio.
AAP reports that Prime Minister Tony Abbott and Immigration Minister Scott Morrison have refused to comment on reports that the Australian navy and customs have either towed back or turned back as many as five boats in the past month.
Mr Abbott has made no apologies for the government's secrecy over its border protection operations, likening the fight against people smugglers to a war.
Mr Morrison noted the UNHCR had been a long-term critic of the coalition's border protection policies, and that the government's actions did not breach Australia's international obligations.
But Greens immigration spokeswoman Sarah Hanson-Young said turning back and towing back boats was "dangerous" and "illegal" and government was "thumbing its nose" at international law.
