Sembrong MP Hishammuddin Hussein wants police to investigate a purportedly fake letter backing him as a prime minister candidate.

"This letter is false and untrue.

"A police report will be lodged today so an immediate investigation can be carried out to determine who is behind this irresponsible act," he said in a Facebook post today.

The letter surfaced a day after Padang Rengas MP Nazri Abdul Aziz admitted to penning a declaration allegedly signed by 25 of 42 BN lawmakers supporting Hishammuddin as their spokesperson instead of BN chairperson Ahmad Zahid Hamidi.

Nazri, however, said the declaration was not meant to back Hishammuddin as prime minister.

The foreign minister has not commented or denied Nazri's allegations.

The purportedly fake letter cites Hishammuddin as stating that the BN supreme council had unanimously backed him to lead the next Malaysian government as its prime minister.

The letter was dated June 22 and supposedly marked as received by Istana Negara officials yesterday.

In it, he also supposedly pledges to appoint current prime minister Muhyiddin Yassin as a member of his advisory council alongside former prime ministers Najib Abdul Razak and Dr Mahathir Mohamad.

The letter includes a list that is supposedly his proposed cabinet line-up which includes MPs and senators from Perikatan Nasional and Warisan as well as Muar MP Syed Saddiq Syed Abdul Rahman.

The list names Hishammuddin as prime minister and finance minister while Azmin Ali and Ismail Sabri Yaakob are purportedly proposed as first and second deputy prime ministers.

Gerakan president Dominic Lau was also listed as Covid-19 vaccinations minister.