The UN refugee agency has warned that Australia could be breaking international law, amid reports that it pushed back to Indonesia boats carrying asylum-seekers.

Adrian Edwards, spokesman for the UN high commissioner for refugees, said on Friday that the agency wanted an explanation after the reports that the Australian navy forced boats back, as well as plans to buy more vessels to bolster such operations.

The UN wants an explanation after reports that aslyum seeker boats have been turned back to Indonesia by Australia. Credit:Sharon Tisdale

"UNHCR would be concerned by any policy or practice that involved pushing asylum-seeker boats back at sea without a proper consideration of individual needs for protection," Edwards said, adding the UN was still seeking details from the government.

"Any such approach would raise significant issues and potentially place Australia in breach of its obligations under the 1951 Refugee Convention and other international law obligations."