SHANGHAI, May 10 (Xinhua) -- All four factories of the U.S. manufacturing company 3M in Shanghai had resumed production by Saturday, sources with the company said, adding that it will continue improving their production capacity.

Since the resurgence of COVID-19 cases in March in Shanghai, 3M has not suspended its East China Distribution Center and the production of medical protective masks at its Caohejing base to ensure the stable supply of anti-epidemic materials, the company said.

"3M has received strong support from the governments at all levels in Shanghai," said Ding Hongyu, president of 3M China. "Now, 3M is gathering the strength of the entire company to actively deploy resources, so as to ensure the closed-loop production of epidemic prevention supplies."

According to a press conference held on May 5, over 70 percent of Shanghai's 1,800-plus major enterprises had resumed work and production as the city's epidemic situation eased.

Key industrial chains such as automobiles, integrated circuits and biomedicine continued to recover and increase production capacity, while leading enterprises have maintained stable production.

On Monday, Shanghai reported 234 confirmed locally transmitted COVID-19 cases and 2,780 local asymptomatic cases, according to the municipal health commission.