Japan on Friday reported 41 new cases of a virus on a quarantined cruise ship and turned away another luxury liner while the death toll in mainland China rose to 636, including a doctor who got in trouble with authorities in the communist country for sounding an early warning about the disease threat.

Following an online uproar over the government’s treatment of Dr Li Wenliang, 34, the ruling Communist Party said it was sending an investigation team to “fully investigate relevant issues raised by the public” regarding the case.

Two docked cruise ships with thousands of passengers and crew members remained under 14-day quarantines in Hong Kong and Japan.

Before Friday’s 41 confirmed cases, 20 infected passengers were escorted off the Diamond Princess at Yokohama near Tokyo. About 3,700 people have been confined aboard the ship.

Prime Minister Shinzo Abe announced on Thursday that Japan will deny entry of foreign passengers on another cruise ship — Holland America’s cruise ship Westerdam, on its way to Okinawa from Hong Kong — because of suspected virus patients found on board. The Seattle-based operator denied anyone had virus.

Abe said the new immigration policy takes effect on Friday to ensure border control to prevent the disease from entering and spreading further into Japan. The ship with more than 2,000 people was currently near Ishigaki, one of Okinawa’s outer islands, and was seeking another port, said Overseas Travel Agency official Mie Matsubara. “Everyone is starting to reject the ship and we are getting desperate,” she said. “We hope we can go somewhere so that passengers can land.” At least four other cruise ships, two foreign and two Japanese-operated, are headed to Japan by the end of the month, Transport Minister Kazuyoshi Akaba said, urging port authorities around the country to turn them away.

Dr Li had worked at a hospital in the epicentre of the outbreak in the central city of Wuhan. He was one of eight medical professionals in Wuhan who tried to warn colleagues and others when the government did not, writing on his Twitter-like Weibo account that on December 3 he saw a test sample that indicated the presence of a coronavirus similar to SARS, which killed nearly 800 people in a 2002-2003 outbreak that the government initially tried to cover-up.

Li wrote that after he reported seven patients had contracted the virus, he was visited on January 3 by police, who forced him to sign a statement admitting to having spread falsehoods and warning him of punishment if he continued.

A copy of the statement signed by Li and posted online accused him of making “false statements” and “seriously disturbing social order.” “This is a type of illegal behaviour!” the statement said.

Li wrote that he developed a cough on January 10, fever on January 11 and was hospitalised on January 12, after which he began having trouble breathing. He also wrote that he had not in fact had his medical license revoked, a reference to the sort of extrajudicial retaliation the communist authorities meet out to rights lawyers and others seen as troublemakers.

“Please rest easy, I will most certainly actively cooperate with the treatment and seek to obtain an early discharge!” Li wrote on January 31. He posted again on February 1, saying he had been confirmed as having the virus.

On Friday, the Global Times, a Communist Party newspaper and usual staunch defender of the authorities, reported that “many said the experience of the eight ‘whistleblowers’ was evidence of local authorities’ incompetence to tackle a contagious and deadly virus.” It quoted Zeng Guang, chief epidemiologist at the Chinese Centre for Disease Control and Prevention, as telling the paper’s editor that “we should highly praise the eight Wuhan residents.”

“They were wise before the outbreak,” Zeng was quoted as saying. The paper also cited online voices saying local authorities owe Li an apology.