BRASILIA, July 11 (Reuters) – Shipping operators at Brazil's No. 2 port sought answers on Friday as to how the docks came to be shut down without warning for eight hours by environmental inspectors, delaying grains and sugar shipments.

The Paranagua seaport, which is situated centrally between the main sugar cane state Sao Paulo and grain-growing regions further south, reopened early on Friday after being shut down by the environmental agency Ibama for operating without a license.

Ibama ordered the port to close on Thursday evening and fined it 4.8 million reais (US$2.7 million) for lacking the environmental license, but a federal judge overruled the order in the early hours of Friday which enabled the facility to operate normally. Commodities exporters at the terminal said they were taken by surprise and were mulling whether they needed to create contingency plans in case the port was closed again.

''Financially there weren't big losses but the worry is that this could happen again for a longer period of time and generate incalculable losses,'' said Luciano Denardi, director of Grano Logistica, which ships around 800,000 tonnes of soy, corn and flour from the terminal each year.

He and other operators were meeting with some of the port's management on Friday afternoon, seeking answers about the closure which could quickly have generated massive costs if ships fell far behind their scheduled itineraries.

The severity of the measure raised questions about regulatory risks in one of the world's biggest commodities producers.

Business leaders have long complained that excessive red tape in obtaining environmental licenses was an obstacle to economic growth in Brazil.

''This was excessive on Ibama's part. There was no need to halt everything,'' Andre Cansian, the port's technical director, told Reuters. ''We had soy and sugar loading yesterday. During this time they couldn't load.''

The port estimated it could have lost around $50 million a day if it had been halted for longer. It handles about $12 billion in merchandise a year.