Spending on reconstruction in Thailand could amount to more than 100 billion baht ($3.3 billion) after the worst floods in half a century damaged large areas of farmland and closed huge industrial estates.

The cost could go far higher if Bangkok, which accounts for 41% of the country’s GDP, is hit by floods, according to prime minister Yingluck Shinawatra.

Monsoon rain, high tides and water flowing down from reservoirs in northern Thailand have killed more than 315 people and had threatened the capital at the weekend but its defensive system of dikes and canals held.

But Bangkok governor Sukhumbhand Paribatra warned the danger was not completely over and that districts in the north of the capital may still face problems over the next 48 hours.

“We don’t want to cause any panic among Bangkokians,” he said. “However, if you want to move valuables or electrical equipment to higher ground for safety reasons, that would be good.”

There have been conflicting signals over the fate of the Nava Nakorn industrial estate north of Bangkok, which has 270 plants and about 270,000 workers. The government told firms to halt operations yesterday as floodwater breached its walls.

At least six big estates have now closed, most of them in the city of Ayutthaya, a World Heritage site north of Bangkok. The floods have halted production at its large auto industrial base and forced closure of its famous historical park of temples.

Residents have complained about contradictory noises from city and government officials, including an evacuation warning in a northern suburb last week that proved to be a false alarm.