* Fire shut plant on Sept. 28

* Plant was supposed to reopen Jan. 1

* Will now reopen in Oct. 2021

OSLO, Oct 26 (Reuters) - Equinor's Melkoeya liquefied natural gas (LNG) plant in Norway could remain closed until October 2021 as extensive repairs are carried out following a fire last month, the company said on Monday.

The plant, also known as Hammerfest LNG, had previously been scheduled to reopen on Jan. 1.

The fire on Sept. 28 in one of the plant's electricity-generating turbines was extinguished after about six hours, Norway's Petroleum Safety Authority said at the time.

"In addition to damage caused by the fire on the air intake on one of the plant's five power turbines, large amounts of sea water from the extinguishing have damaged other auxiliary systems such as electrical equipment and cables in the plant," Equinor said in a statement.

"It is the scope of work of these consequential damages that are considered the most extensive and the duration of the shutdown will depend on the delivery time of necessary equipment," Equinor said.

Progress will also be affected by restrictions related to the pandemic, the company added.

Norwegian police and the country's Petroleum Safety Authority are both investigating the fire, with Equinor also conducting its own study.

Europe's only large-scale LNG plant is located outside the Arctic town of Hammerfest and can process 18 million cubic metres (mcm) of gas per day. The gas is piped in from the offshore Snoehvit field some 160 km (100 miles) away in the Barents Sea.

After cooling the gas until it turns to liquid, it is shipped in tankers to energy markets in Europe and Asia.

Unlike other Norwegian gas fields, which export their hydrocarbons to Europe via pipelines, Snoehvit is only linked to the LNG plant and thus unable to produce while the plant is offline.

Snoehvit is owned by Equinor, Total, Neptune Energy, Wintershall Dea and Norwegian state-owned firm Petoro. (Editing by Gwladys Fouche and Jason Neely)