A total of 26 German journalists based in China wrote a joint letter to Chancellor Angela Merkel on Sunday, complaining about their limited freedom when reporting in the country. Experts said that China is opening up its media environment, little by little.

In the letter, the reporters said some Chinese officials had been "willfully obstructing their work," by threatening not to renew their visas, bullying their Chinese news assistants and pressuring people into rejecting interview requests.

They called on Merkel, who will arrive in Beijing on Thursday for a two-day visit, to "discuss these issues at the highest governmental level" and requested "the same working conditions that Chinese journalists enjoy in Germany."

Yu Guoming, a professor of the School of Journalism and Communication at the Renmin University of China, told the Global Times that both Chinese and foreign reporters have problems obtaining vital information on some sensitive topics that might harm local officials' interests.

Zhou Fancai, an investigative reporter from Oriental Outlook magazine, said it is not uncommon for many Chinese reporters to be beaten by those who fear their personal interests might be threatened due to media exposure.

"It is not targeted only at foreign reporters," said Zhang Zhi'an, an associate professor with the School of Communication and Design at Sun Yat-Sen University. "No matter whether in China or foreign countries, investigations and supervision of public power will sometimes be met with obstruction."

Zhou said that in some cases, local governments may treat foreign reporters with more care than their Chinese counterparts, for fear of creating diplomatic tensions if they upset foreign journalists.

"The fact is China has opened up its media environment and improved its media situation in the past decades, but the openness cannot happen all at once. Instead, the media situation is improving little by little," Zhang Yiwu, a professor of cultural studies at Peking University, told the Global Times. 

Yu called on officials to improve the media environment and keep an open, transparent flow of information with both the press and the public when emergencies occur. 

Peter Ford, president of the Foreign Correspondents' Club of China, told the Global Times in a letter that "foreign correspondents enjoy much more reporting freedom today than they did 10 years ago." However, Ford added that foreign reporters are still barred from some areas of China.

A reporter from ARD Radio, who was among the 26, refused to comment on the issue when contacted by the Global Times.

The Ministry of Foreign Affairs also declined to comment.

The complaint came after several foreign journalists were harassed or beaten in China over the past two months.

A Japanese reporter from Asahi Shimbun was beaten by police when covering a demonstration in Jiangsu Province in July. In May, Al Jazeera's English channel shut down their bureau in Beijing after Chinese authorities refused to renew the press credentials and visa of their correspondent, Melissa Chan.