A DAP lawmaker has called on Prime Minister Najib Abdul Razak to explain the delay in sending Muhammad Rizalman Ismail to New Zealand to face sexual assault charges.

"He must tell us what has happened in the last five months and whether his government will still honor its pledge to send Rizalman back to New Zealand," said Gobind Singh Deo.

He said Najib must acknowledge the sensitivities involved given the nature of the complaint in this case.

"It is to the benefit of all concerned that the matter be dealt with expeditiously. It is particularly so as to ensure justice for both the complainant and the accused in this case," he added.

The Puchong MP was responding to reports that Rizalman, who was previously attached to the Malaysian High Commission in New Zealand, was discharged from psychiatric evaluation from a military hospital at the end of July this year.

He also recalled that Najib also said that Malaysia would send him back to New Zealand to facilitate investigations.

"Putrajaya must recognise the fact that it cannot run away from criticism over its handling of this matter.

"It has been some five months now since the alleged incident but we don't yet see any headway in the matter. This sends the wrong signal," he said in a statement.

Gobind said this suggested that Putrajaya is either "plainly incompetent and unable to deliver on its pledges" to foreign countries or that it is "dragging its feet" in the matter.

"All in all, it reflects poorly on our country," he added.