Deputy Prime Minister Ahmad Zahid Hamidi has expressed support for Hishammuddin Hussein over his appointment as a special functions minister.

His backing comes amid speculation by opposition politicians that Zahid's political ambition is at risk.

"I support the new portfolio assigned to assist the prime minister in missions and special tasks to strengthen bilateral relations (with other countries) and also specific tasks that will lead to the smooth administration of the government," he was quoted as saying by Bernama.

Zahid said the appointment was spot on and expressed confidence that Hishammuddin would be up to the task.

This afternoon, Prime Minister Najib Abdul Razak had announced Hishammuddin's appointment, which takes immediate effect.

He also said that Hishammuddin, who is his cousin, would continue helming the defence portfolio as well.

Soon after the announcement, several opposition leaders speculated that Najib was prepping Hishammuddin to take over the leadership reins.

PKR vice-president Rafizi Ramli said the appointment did not bode well for Zahid, who was appointed deputy prime minister in July, 2015 after Najib dropped Muhyiddin Yassin from the cabinet.

Parti Amanah Negara (Amanah) deputy president Salahuddin Ayub claimed that the appointment indicated Najib's exit plan and Hishammuddin's ascension to the top post.

According to Salahuddin, it would not come as a shock if Zahid is sacrificed to ensure Najib and Umno's survival.

However, Hishammuddin has dismissed the speculations, and warned all quarters against exploiting his appointment to cause a rift in the Najib administration.