Clean-up work is under way at four industrial estates in Thailand's central Ayutthaya province as water has receded after devastating floods last month, and some factories are already back at work, officials said on Monday.

Tawee Narissirikul, deputy governor of Ayutthaya province and head of its industrial rehabilitation committee, said good progress had been made in restoring industrial zones including Rojana Industrial Park, Hi-Tech, Bang Pa-In and Factory Land.

We are seeing fast progress, Tawee told Reuters. Factory Land, for instance, is now 95 percent dry with only a little bit of water in front of the estate left to be drained.

Twelve companies in the estate are back in business and clean-up work is under way for the remaining plants, he added.

The water level at Bang Pa-In industrial estate -- where hard drive maker Western Digital has two manufacturing facilities -- has fallen to 70 cms (27 inches) from a peak of 1.80 metres after authorities started draining it out on November 8.

Tawee said a big clean-up would start at Bang Pa-In on November 20 and some plants might restart from November 25.

Thailand's worst flooding in at least five decades has swamped seven estates north of the capital, disrupting global supply chains. The floodwater running down from the north of the country has killed 562 people since July.

Even though water was now receding, supply disruption would remain a problem for some time, said Kobkarn Wattanavrangkul, chairwoman of Toshiba Corporation's Thai unit, adding it was too early to estimate the impact.

We don't aim to resume operations until early next year, she said, referring to its plants in Bangkadi and Nava Nakorn Industrial Park, both in central Pathum Thani province.

WATER RECEDING

Two estates in greater Bangkok have come under threat this month but may escape serious flooding.

Water in canals by Bang Chan industrial estate had receded on Monday and more firms had decided to reopen their factories after protectively closing them last week, said Yongyuth Thongsuk, deputy permanent secretary at the Industry Ministry.

More companies in the estate have resumed their plants, so we're down to 12 closed from 16 last week, he told Reuters.

Bang Chan, 15 km (9 miles) north of Suvarnabhumi Airport, is home to 93 factories run by local and international companies including Nestle SA, instant noodle maker YumYum and President Bakery Pcl, which makes buns for McDonald's.

The situation at the Lat Krabang estate has stabilised although water has surrounded the zone for days.

Unilever, Isuzu Motors, Johnson & Johnson and Cadbury Pcl are among those running 231 factories employing 48,000 workers at Lat Krabang, located 10 km from the airport, which is itself protected by a huge dike and functioning normally.

Thailand is the main Southeast Asian manufacturing hub for Japanese auto-related companies and the floods have caused a shortage of parts that has idled production in Japan and elsewhere, including North America for some manufacturers.

Toyota Motor Corp said that its production in Japan would return to near normal levels next week after the floods disrupted parts supplies.

Mitsubishi Motors Corp resumed production at its Thai plants from Monday.

Honda Motor Co, the hardest hit of the Japanese car firms, said it would take longer for its production to be up and running again.

There is no schedule for Honda to resume production at this point, Raewadee Rakpathum, a spokeswoman for Honda Motor Co's Thai unit, said.

Honda had to shut its assembly plant in the central province of Ayutthaya, closing down 4.7 percent of its global output.

Other big car producers tend to have assembly plants in the southeast, away from the flooding.

(Editing by Alan Raybould)