Image caption The anniversary will be celebrated on 1 July

China has ordered TV stations across the country not to air any detective shows, spy thrillers or dramas about time-travel for the next three months.

All have been ordered off-air with immediate effect.

An official at China's state TV regulator confirmed to the BBC that the verbal order had been made.

China's Communist Party is preparing to mark 90 years since its founding and the authorities want TV stations to air programmes praising the party instead.

The government wants China's one billion television viewers to tune in to a wholesome diet of patriotic propaganda that will glorify the party ahead of the anniversary on 1 July.

Short notice

Wang Weiping, the deputy chief of the drama department at China's state TV regulator, called this a "propaganda period".

There are "dozens of good TV dramas related to the founding of the party" that stations can broadcast, he told the Beijing News.

Oriental TV in Shanghai told the BBC it was postponing its spy drama Qing Mang, due to air in 10 days time. It will be replaced by a comedy about mothers and their daughters-in-law.

An official at Oriental TV said the government often issues orders about which programmes should and should not be aired.

"TV stations quite often have to rearrange the TV drama broadcasting schedule at short notice. We are always ready to rearrange things. And we normally don't ask why," Ouyang Lina of Oriental TV told the BBC.

So what many Chinese viewers will now see in the coming weeks are shows like the specially-made historical drama Dong Fang.

According to the show's publicity, it follows China's Communist leader Mao Zedong between the founding of the People's Republic of China and his second visit to the former Soviet Union 12 years later.

And the show charts the development of Marxism-Leninism in China and the achievements of the Communist Party in politics, military, culture, economics and diplomacy.