Image caption The open letter comes just days before Xi Jinping takes over as China's president

Some of China's most prominent scholars, journalists and activists have released an open letter urging leaders to implement political reforms, for the second time in three months.

More than 100 people signed the open letter urging Beijing to ratify an international human rights treaty.

The letter was posted on several prominent Chinese websites and blogs.

It comes just days before Chinese leaders gather for the annual parliamentary session in Beijing.

At the meeting, new Communist Party leader Xi Jinping will be installed as China's president, taking over from Hu Jintao, completing the 10-yearly power transition.

'Feasible goal'

"We solemnly and openly propose the following as citizens of China," the letter begins, "that the International Covenant on Civil and Political Rights (ICCPR) be ratified, in order to further promote and establish the principles of human rights and constitutionalism in China."

Signatories to the letter Dai Qing: Activist and writer. A one-time Communist Party member, Dai quit the party in 1989 after her book, Yangtze! Yangtze!, protesting the construction of the Three Gorges dam, was banned by the authorities. Since then, she has spoken out on a variety of environmental and political issues.

Activist and writer. A one-time Communist Party member, Dai quit the party in 1989 after her book, Yangtze! Yangtze!, protesting the construction of the Three Gorges dam, was banned by the authorities. Since then, she has spoken out on a variety of environmental and political issues. Pu Zhiqiang: Human rights lawyer. Pu is a Beijing-based human rights lawyer with a long list of sensitive clients, including renowned artist Ai Weiwei and Tibetan environmentalist Karma Samdrop.

Human rights lawyer. Pu is a Beijing-based human rights lawyer with a long list of sensitive clients, including renowned artist Ai Weiwei and Tibetan environmentalist Karma Samdrop. Wang Keqin: Investigative journalist. Wang is a top investigative reporter in China. For decades, he has made his name exposing crime and corruption at all levels of Chinese society.

Investigative journalist. Wang is a top investigative reporter in China. For decades, he has made his name exposing crime and corruption at all levels of Chinese society. Mao Yushi : Economist. Mao is a an outspoken proponent of free markets and a more transparent political system in China. Mao is one of the founders of the Unirule Institute of Economics, an independent think tank that advocates for political and economic reform in China.

: Economist. Mao is a an outspoken proponent of free markets and a more transparent political system in China. Mao is one of the founders of the Unirule Institute of Economics, an independent think tank that advocates for political and economic reform in China. He Weifang: Legal Scholar. A professor at the Peking University Law School, He Weifang has made his name pushing for legal reform and the establishment of the rule of law within China.

The ICCPR is part of the International Bill of Human Rights created by the United Nations. It calls for basic civil and political rights of individuals, including freedom of religion, freedom of speech and freedom of assembly.

Beijing signed the treaty in 1998 but the Chinese parliament has never ratified the document.

The open letter was signed by many prominent thinkers in China, including economist Mao Yushi, legal scholar He Weifang and Dai Qing, an outspoken political activist.

In December, many of the same people also signed a strongly worded open letter demanding political reform within China, including an independent judiciary and meaningful democratic change.

"If reforms to the system urgently needed by Chinese society keep being frustrated and stagnate without progress," December's letter warned, "then official corruption and dissatisfaction in society will boil up to a crisis point and China will once again miss the opportunity for peaceful reform, and slip into the turbulence and chaos of violent revolution."

The language in the more recent letter was much more conciliatory, acknowledging the difficulties of enacting meaningful political change within China while also emphasising that signing the ICCPR would be a "feasible" goal for Chinese leaders.

In an interview with the BBC, investigative journalist Wang Keqin said he was confident China's leaders would ratify the ICCPR during the upcoming parliamentary session, a goal he acknowledged was "very mild and conservative".

"We don't dare to dream that China will make a lot of progress in one giant leap," Mr Wang said. "The country develops step by step and our efforts are also aimed at changing things step by step. This is the embarrassing situation we are in now."

He did not want to identify the person who first wrote the letter and collected the signatures, blaming his reluctance on "China's special situation".

According to the China Media Project, a group based at Hong Kong University which monitors the Chinese media, this week's letter was scheduled to be released on Thursday.

However the authorities reportedly heard about the letter early, leading its supporters to bring publication forward by two days. Mention of the letter has since disappeared from many internet sites within China.