Emergency measures to help the thousands of holidaymakers left stranded on Hainan Island after heavy fog disrupted ferry services to the Chinese mainland have officially been lifted.

The number of vehicles waiting to cross the Qiongzhou Strait to Guangdong province has returned to normal, authorities in Haikou, the island province's capital, said on Monday.

Heavy mist over the strait on Feb 19 resulted in a line of about 20,000 cars stretching 20 kilometers by Tuesday. The island's three ferry ports are the only access for vehicles.

To ease the gridlock around the ports, the city issued emergency measures, setting up 24-hour command centers along major roads manned by government officials as well as 58,000 police officers, cleaners, medical workers and volunteers.

Stranded motorists were provided food and blankets, and about 944 people received medical treatment, the city government said, adding that regular traffic updates were sent through various media channels.

In the past week, 138,902 vehicles and 713,820 passengers have been ferried to Guangdong, data provided by the Haikou government show.

"We've done our best, but we know there must have been things we overlooked," Deng Lisong, a senior Haikou official, said on Sunday night. "We welcome criticism and suggestions to help us improve our services."

Deng thanked the island's residents for their efforts, and apologized to them for any inconvenience.

The strait is forecast to experience heavy fog again between midnight on Tuesday and midday on Thursday, and drivers have been warned to expect delays.

Hainan is a popular destination during the annual Chinese New Year holiday. This year, it received 5.67 million tourists, official statistics show.