Former Liberal leader Malcolm Turnbull has stepped back into the political fray savaging Kevin Rudd’s position on the emissions trading scheme as ‘‘the greatest act of political gutlessness anyone has ever seen’’.

Mr Turnbull said his decision to recontest his eastern Sydney seat of Wentworth at this year’s election was sparked by the ‘‘extraordinary conduct of the Rudd government’’, in particular the prime minister’s recent decision to shelve the emissions trading scheme.

‘‘He does not have the courage of his convictions, he has walked away from his climate change policy and he now has no climate change policy at all,’’ Mr Turnbull said, describing Mr Rudd’s decision as ‘‘the greatest act of political gutlessness anyone has ever seen’’.

‘‘I believe political leaders have to have guts and have to have courage and that is the reason I am stepping back into the fray and running again here in Wentworth.’’

Mr Turnbull said he stands by his support for the emissions trading scheme, which led to him losing the party’s leadership to Tony Abbott last December.