A Kiwi cyclist faces a "significant" ban from all sports after failing a doping test for the second time, Drugfree Sport says.

The New Zealand doping agency says Karl Murray tested positive for the anabolic agent clenbuterol following testing at the Tour of Northland in March this year.

Murray had already been given a two-year ban from the sport in 2014 after testing positive to nandrolone and testosterone in New Caledonia and Drugfree chief Nick Paterson says he now faces a lengthy penalty for his second offence.

"Mr Murray clearly did not learn the lessons from his first ADRV, and he now faces a significant ban from all sport," he said.

"Those who consciously choose to go against the spirit of sport are not only doing themselves a disservice, but undermining the efforts of other athletes - in this case his competitors in the Tour of Northland."

Murray was selected for a control test on March 18 and both his A and B - or second - samples came back positive, Drugfree Sport said.

His original ban was imposed by the Anti-Doping Commission of New Caledonia and was recognised in New Zealand in 2015.

The agency said clenbuterol was used by athletes who wanted to lower body fat, without bulking up.