Visiting Wuhan in a blue protective suit and mask, Li praised medics, said 2500 more workers would join them in the next two days, and visited the site of a new hospital to be built in days.
The most senior leader to visit Wuhan since the outbreak, Li was shown on state TV leading medical workers in chants of “Wuhan jiayou!” – an exhortation to keep their strength up.
On China’s heavily censored social media, officials have faced mounting anger over the virus, which is thought to have come from a market where wildlife was sold illegally.
In rare public self-criticism, Wuhan Mayor Zhou Xianwang said the city’s management of the crisis was “not good enough” and indicated he was willing to resign.
The central Chinese city of 11 million people is in virtual lockdown and much of the province of Hubei, home to nearly 60 million people, is under some kind of travel curb.
A few cases linked to people who travelled from Wuhan have been confirmed in a dozen countries, from Japan to the US, where authorities said they had 110 people under investigation in 26 states.
US President Donald Trump has offered China whatever help needed to control the outbreak, which has stranded tens of millions during the biggest holiday of the year and rattled global markets.
“We are in very close communication with China concerning the virus,” tweeted Trump, who waged a bruising 18-month trade war with Beijing until a recent truce.
“We have offered China and President Xi (Jinping) any help that is necessary. Our experts are extraordinary!”
Sri Lanka was the latest country to confirm a case of the virus.
Authorities in China have limited travel and extend the week-long Lunar New Year holiday – when millions traditionally travel by rail, road and plane – by three days to limit the spread of the virus.
During the 2002-2003 outbreak of Severe Acute Respiratory Syndrome (SARS), which originated in China and killed nearly 800 people globally, air passenger demand in Asia plunged 45 per cent.
The travel industry is more reliant on Chinese travellers now.