Tony Abbott has urged “rebellious” conservative colleagues not to leave the Liberal Party and risk delivering the government benches to Labor.

The former prime minister has written in The Australian on Friday that Coalition MPs unhappy with the government’s direction should “stay and fight” in the party, saying it’s better to “fix it, not to leave it”.

He’s said it would be a “catastrophic mistake” for MPs to abandon the party and so deliver the opposition “at least two terms” in government.

“We don’t owe the party slavish obedience but we certainly owe it respect and loyalty,” Mr Abbott wrote.

If we think the party is headed in the wrong direction or is making a big mistake, our duty is to try to fix it, not to leave it.”

Mr Abbott’s message comes as the party becomes increasingly concerned that conservative senator Cory Bernardi is about to split off to spearhead a new conservative force.

“Right now, a combination of unhappiness with what the Liberal Party has done to itself and excitement about the Trump insurgency in the United States is driving interest in a new political alignment here,” Mr Abbott wrote.

But he said for all its faults and failings, the Liberal-National coalition was Australia’s “best hope of sensible centre-right government” and it was much easier to repair an existing party than to form a new one.