“We urge a full and transparent investigation” into the accusations, a spokeswoman for the EU’s diplomatic service told AFP on Wednesday.
Peng, a 35-year-old Wimbledon and French Open doubles champion, was not seen for more than two weeks following her allegations that former vice-premier Zhang Gaoli, now in his 70s, forced her into sex during a years-long on-off relationship.
On Sunday, official photos of a Beijing tennis tournament showed Peng among attendees, and she participated the same day in a video call with the head of the International Olympic Committee.
Last week, a Chinese state-run media outlet published what it said was a screenshot of an email by Peng which stated that the accusations made by tennis star were “not true” and that “everything is fine” with her.
“We have seen Peng Shuai’s presumed remarks and footage from her public appearance. However, the reports, both about the allegations of abuse and the fact that she had not been seen for two weeks, remain very worrying,” the EU spokeswoman, Nabila Massrali, said in a statement to AFP.
“We are not in a position to comment on the allegations themselves, but we urge a full and transparent investigation,” she said.
The United Nations, the United States and Britain have all also called for proof of Peng’s whereabouts and well-being.
China’s foreign ministry reacted on Tuesday by saying that “people should stop deliberately and maliciously hyping up” the controversy around Peng.
But Massrali said “the requests for reliable information are legitimate and remain”.
She said: “We still call on the Chinese government to provide independent and verifiable proof of her well-being and whereabouts.”