Whether Muhyiddin Yassin can carry out his role as Umno deputy president is at the discretion of his boss Najib Abdul Razak, said Selangor Umno information chief Zein Isma Ismail.

"It is true that in the party constitution, the duty of the Umno deputy president is to assist the president.

"However, it is up to the president whether he wants to give that role to him (the deputy) or not.

"Surely the party president will not delegate responsibilities if he finds that his deputy is incapable of carrying out the given duties," he told Malaysiakini .

Zein was asked to respond to Muhyiddin's complaint last Saturday where he claimed Najib was preventing him from carrying out his duties as Umno deputy president.

Muhyiddin was removed as deputy prime minister in July last year for being critical of Najib's scandals but retains his position as Umno deputy president, albeit being sidelined.

Zein, who is also Subang Umno chief, dismissed Muhyiddin's complaint that he was being blocked from carrying out his duties and instead accused the Pagoh MP of not using his position "appropriately".

"He is not being blocked, he still has his position. It is just a matter of his interpretation.

"He can still voice out in the Umno supreme council but he has not used the opportunity to do so," he said.

Zein also defended the party's earlier decision not to allow Muhyiddin to officiate the party's functions which he said was a role not enshrined in the party constitution but merely a tradition which can be changed according to the times.

He claimed that Muhyiddin was complaining because he was still slighted by the fact that he was not allowed to speaking during the Umno general assembly last year.

If Muhyiddin loved Umno, then he should not complicate matter further, Zein added.

"Resolve the matter through discussion so that it will not bring trouble to us (Umno)," he said.