Tony Abbott has been told to keep his head down or he risks trashing his own legacy.

The former Howard government minister Peter Reith has urged Abbott to do some soul-searching on his recent behaviour.

“He’s doing himself a disservice and he’s doing a disservice to the country,” Reith told Sky News on Monday. “He needs to keep his head down for his own sake otherwise he will be trashing his own reputation.”

There are reports Abbott will embark on his own marginal seat tour after being snubbed over a proper campaign role in what is likely to be a 2 July double-dissolution election.

Abbott has also penned a 3,706-word essay for Quadrant magazine defending his foreign policy and defence credentials. He defended cosying up to former Sri Lankan president Mahinda Rajapaksa in order to stop the flow of asylum seeker boats.

Abbott hailed his call not to join the “human rights lobby against the tough but probably unavoidable actions taken to end one of the world’s most vicious civil wars”.

“The government simply had to stop the boats. Our national interest and our self-respect as a country demanded it,” he said.

The United Nations has been pushing for an investigation into allegations that up to 40,000 ethnic Tamil civilians were killed by Sri Lankan government troops in the final months of fighting in the civil war, which ended in 2009.

The acting opposition leader, Tanya Plibersek, was unimpressed with Abbott’s analysis.

“I think it would be a good thing for the foreign minister to have a few words to Mr Abbott,” she told reporters in Sydney.

One reason Australia is so well-regarded internationally across history is because it is a responsible international citizen.

“Part of that means standing up against human rights abuses,” she said.