Police are hunting down the source of the poison pen letter calling on Prime Minister Datuk Seri Najib Tun Razak to step down, said Deputy Prime Minister Datuk Seri Ahmad Zahid Hamidi.

Datuk Seri Ahmad Zahid, who is also Home Minister, said the person or persons responsible for spreading the letter on social media had committed three offences, namely falsifying his signature, using an official government letterhead and resorting to defamation.

He said police had received no less and 20 complaints relating to the poison pen letter and had been informed that the police and the Malaysian Communications and Multimedia Commission were carrying out thorough investigations to track down the person or persons responsible.

"I am certain that whoever did this will face the full brunt of the law," he told reporters after opening the Indian Progressive Front's 24 general assembly here today.

Datuk Seri Ahmad Zahid was asked to comment on the disemmination of the appendix of a poison pen letter containing the list of names a new cabinet with Ahmad Zahid named as Prime Minister in social media and the WhatsApp application.

The poison pen letter also urged all Cabinet members to pressure Datuk Seri Najib into stepping down as prime minister.

Datuk Seri Ahmad Zahid, who is also UMNO Vice President but performing the duties of Deputy President, said the letter was slander to create tension in BN and UMNO.

"They are envious of the close relationship between the prime minister and I which developed since Najib was still Youth and Sports Minister and also UMNO Youth chief. They are jealous of the unity and solidarity in UMNO. So, they want to pit the leaders against one another.

"They know that if they can drive a wedge between us (Datuk Seri Najib and him), their aim is achieved," he said.

Datuk Seri Ahmad Zahid said the poison pen letter did not have much impact on UMNO and BN because many did not believe the letter as the letterhead and his signature were falsified.

In addition, he said, the list of posts mentioned did not comply with protocol or guidelines.

Yesterday, Datuk Seri Najib, who is also UMNO President, said the dissemination of such rumours was an effort to damage the close ties between him and the Deputy Prime Minister. -- BERNAMA