By Yawen Chen and Brenda Goh

BEIJING/SHANGHAI (Reuters) - The Chinese city of Wuhan raised its death toll from the novel coronavirus by 50% on Friday, bringing its total to 3,869, amid doubts about the accuracy of China's data on the disease as global cases mount.

The central city where the virus first appeared in humans late last year added another 1,290 fatalities to the 2,579 previously counted as of Thursday, reflecting incorrect reporting, delays and omissions, according to a local government taskforce in charge of controlling the coronavirus.

Reflecting the additional deaths in Wuhan, China revised up its national death toll later on Friday to 4,632.

The revision follows widespread speculation that Wuhan's death toll was significantly higher than reported.

Rumours of more victims have for weeks been fuelled by pictures of long queues of family members waiting to collect ashes of cremated relatives and reports of thousands of urns stacked at a funeral home waiting to be filled.

"In the early stage, due to limited hospital capacity and the shortage of medical staff, a few medical institutions failed to connect with local disease control and prevention systems in a timely manner, which resulted in delayed reporting of confirmed cases and some failures to count patients accurately," state broadcaster CGTN quoted an unidentified Wuhan official as saying.

Suspicion that China has not been transparent about the outbreak has risen in recent days, with U.S. President Donald Trump on Wednesday expressing scepticism about its previously declared death toll of about 3,000.

"Do you really believe those numbers in this vast country called China, and that they have a certain number of cases and a certain number of deaths; does anybody really believe that?” he said.

Some experts, however, believe fatality numbers in many other countries fail to show the real toll because some people have died from COVID-19, the disease caused by the virus, without being tested or going to hospital, so are not included in coronavirus tallies.

Wuhan's total number of cases was revised up by 325, suggesting that some of the new deaths had been recorded as cases but not confirmed as fatalities, taking the total number of cases in the city of 11 million people to 50,333, or about 60% of mainland China's total.

QUESTIONS

The topic "Wuhan revises its death toll" was one of the most read on China's Weibo microblogging platform, which is heavily moderated.

Many commentators praised the government for admitting its mistakes and correcting them, though some still questioned the numbers and one urged other provinces to reassess their data.

Doctors and government officials in Wuhan have been repeatedly questioned about the accuracy of the death toll by journalists on government-arranged trips.

Some of those officials acknowledged that people may have died without being counted in the chaotic early days of the outbreak, before testing was widely available.

"There couldn't have been many because that was a very short period," Wang Xinghuan, head of one of two field hospitals built for the outbreak, told reporters in Wuhan on April 12. He stressed that he was not speaking for the government.

Before the revised Wuhan numbers were released, China said it had recorded 26 new cases of the coronavirus on Thursday, down from 46 cases a day earlier, according to the National Health Commission.

It brought the total number of cases in mainland China to 82,367.

Of the new cases, 15 were imported infections, the lowest since March 17. The remaining 11 confirmed cases were locally transmitted, down from 12 a day earlier. The number of new asymptomatic cases increased to 66 from 64 a day earlier.

China does not include patients with no clinical symptoms such as a cough or a fever in its tally of confirmed cases.

No new deaths were reported.

(Reporting by Yawen Chen and Brenda Goh; Additional reporting by Ryan Woo, Catherine Cadell, Stella Qiu, Lusha Zhang, Se Young Lee and the Shanghai newsroom; Writing by Engen Tham; Editing by Tony Munroe, Robert Birsel)