The Chinese reporter was jailed on Monday after her coverage of the government's handling of the coronavirus pandemic. Her imprisonment comes as the EU is set to ink a major investment deal with Beijing.

The European Union on Tuesday demanded that China release citizen journalist Zhang Zhan and several other jailed reporters, lawyers and human rights champions. 

The EU statement was issued just ahead of Brussels signing a major investment pact with Beijing, despite concerns about China’s labour and civil rights record.

"Prior to her detention, Zhang Zhan had been reporting about the coronavirus pandemic in Wuhan," EU foreign policy spokesman Peter Stano said in a statement.

"According to credible sources, Zhang has been subject to torture and ill-treatment during her detention and her health condition has seriously deteriorated. It is crucial that she receives adequate medical assistance."

Zhang was jailed on Monday for four years over allegations of "picking quarrels and provoking trouble," her lawyer said.

EU steps up pressure on Beijing 

The EU also demanded the release of Yu Wensheng, a human rights lawyer jailed on December 13.

Yet officials in Brussels are continuing talks over a major investment pact with China, which is reportedly set to be signed this week.

Some MEPs have expressed concern that the deal, seven years in the negotiation, sends the wrong signal on human rights.

China hopeful of a deal with the EU

A spokesperson for Chinese foreign ministry said on Tuesday that hopes are high that a deal can be struck "at an early date."

Negotiations first started back in 2014 but they have remained blocked for years.

Outgoing US President Donald Trump sparked a trade war with Beijing, by slapping a number of tariffs and sanctions on Chinese-made products.

Donald Trump’s administration targeted a number of technology companies from China as threats to national security.

Last week, the US placed export restrictions on more than 100 Chinese and Russian companies with alleged military ties.

The White House is known to have had concerns about the liberalisation deal over security concerns. China wants access to the EU energy market.

Ties have also been strained over China's crackdown on civil liberties in Hong Kong, a former British colony.

US President-elect Joe Biden also warned EU officials about pressing ahead with forging close with the Chinese state.

Speaking from his transition headquarters on Monday, Biden said: “As we compete with China and hold China’s government accountable for its abuses on trade, technology, human rights and other fronts, our position will be much stronger when we build coalitions of like-minded partners and allies."

MEPs would need to give their approval before the deal can take effect.