The former prime minister, Tony Abbott, and his wife received free return tickets to the United States from a far-right Christian group that lobbies against same-sex marriage and abortion.

In January Abbott flew to the US to address the Alliance Defending Freedom. The organisation takes a hardline stance on abortion and marriage equality.

The organisation also has a reputation for funding litigation involving same-sex marriage and abortion. It has intervened in the supreme court in the US, in one case to actively defend the criminalisation of gay sex.

Abbott updated his parliamentary pecuniary interest register on Friday to state that he received “two return flights from Australia to the United States of America” that were provided by the organisation. The flights were provided for him and his wife, Margie Abbott.

The Hon Tony Abbott has updated the interests register. https://t.co/JwIIH16hrQ — DisclosureBot (@AusDisclosure) February 11, 2016

During the trip Abbott also received an upgrade to a privately funded hotel room in Washington and accommodation at the consul-general’s private residence in New York.

Parliamentarians are permitted to receive flights and other gifts from organisations as long as they declare the interests on the parliamentary pecuniary interest register.

Abbott has embarked on a fledgling career on the international speaker circuit since losing the prime ministership, and is listed on the Washington Speakers Bureau as one of the “world’s greatest minds”. His speakers fee is listed as more than $40,000.