The Prime Minister says a Nationals MP who has come under fire for excessive travel to the Philippines has not been back to that country "on his watch".

Key points: George Christensen says he is the victim of a smear campaign regarding travel to Asia

George Christensen says he is the victim of a smear campaign regarding travel to Asia Media reports reveal he spent more time in the Philippines than Parliament in 2016 and 2017

Media reports reveal he spent more time in the Philippines than Parliament in 2016 and 2017 PM Scott Morrison says he expects MPs to be "in their electorates doing their job"

Media reports revealed conservative MP George Christensen, who in December identified himself as the politician at the centre of allegations about travel to South-East Asia, had spent more time in the Philippines than Parliament House for two years running.

News Corporation reported the Nationals MP made 28 trips to the Asian nation within a four-year period.

"All I can say is George hasn't spent a day in the Philippines since I've been Prime Minister. Not a day," Prime Minister Scott Morrison said.

Mr Christensen described the reports as a smear campaign but Mr Morrison took a veiled swipe at the outspoken Queensland MP.

"I expect members to be in their electorates doing their job," he said.

Mr Christensen, in a statement, insisted his travel had been cleared of any wrongdoing.

"The Herald Sun ran a fake news smear campaign last year that was based on gossip from Labor and a former very senior Liberal MP and that was proven false by none other than the AFP," he said.

When Mr Christensen outed himself last year, he admitted he had been approached by the Australian Federal Police over his frequent trips to the Philippines.

The Australian Federal Police (AFP) later confirmed it couldn't proceed to an investigation as there was no evidence to suggest Mr Christensen had committed a crime.

"At no time was Mr Christensen formally interviewed in relation to child abuse material, unlawful videos, child abuse allegations, or any other criminal matter," the AFP said in a letter the ABC has viewed.

Federal Labor leader Bill Shorten said the travel reports showed Mr Christensen had enjoyed almost three times as much annual leave as most workers.

"The Australian worker gets four weeks annual leave a year," he said.

"Mr Christensen seems to have pioneered the 11 weeks' annual leave condition in the Australian workplace.

"What worries me is what he's not doing in North Queensland."

But Cabinet minister Matt Canavan jumped to his Nationals colleague's defence.

"I think this is a massive beat-up and an invasion of his privacy," he said.

"His fiancee is from the Philippines. He's done a lot of charity work through his church."

Labor senators have offered varying takes on Mr Christensen's travel, with Queenslander Murray Watt saying Mr Christensen had been dubbed the "Member for Manila" by colleagues.