The media in Cambodia has been ordered to write the full title of strongman Hun Sen in all reports, a lengthy honorific loosely translated as 'glorious, supreme prime minister and powerful commander'.

The wily and combative Hun Sen has ruled impoverished Cambodia for three decades, steering it from the ashes of civil war into a relatively fast-growing economy.

But critics say he is increasingly intolerant of dissent, as he eyes elections in two years that could see his support drain, in particular among young Cambodians. 

Starting in July all Cambodia-based media have been told to use the royally-bestowed honorific "Samdech Akka Moha Sena Padei Techo Prime Minister Hun Sen" on first reference.

While it has no exact English translation, the words taken together mean "glorious, supreme prime minister and powerful commander" and are a Khmer title reserved for top leaders.

"The ministry has noticed that some media outlets have missed or forgotten to use the titles," a letter by the Ministry of Information and distributed to the media on Thursday read.

"Particularly the title of Samdech (lord) given to great leaders of the nation."

Phos Sovan, director of the ministry's information and broadcasting department, said all eight titles had to be used on first reference to the premier.

Those who fail to do so could see their media permits pulled or other face other unspecified "actions".

Critics accuse Hun Sen of brooking no dissent, routinely cracking down on opposition lawmakers and activists.

In recent months he has embarked on something of PR makeover, reaching out to younger Cambodians with a stream of daily updates on his official Facebook page.