SWISS mining giant Glencore has announced plans to close its West Wallsend Colliery, axing more than 300 jobs.

The decision, announced on Thursday afternoon, to close the underground mine in mid-2016 was prompted by the struggling coal sector and economic conditions.

Thousands of jobs have been cut from the Hunter’s coal industry as a slump in prices cools future investment.

A Glencore statement said the West Wallsend closure was ‘‘consistent’’ with ‘‘life of mine planning’’ and workers had been told.

‘‘The closure will occur some months earlier than originally scheduled, following Glencore’s decision not to mine an approved longwall beneath cliff lines, terraces and steep sections of the Sugarloaf State Conservation Area,’’ the company said.

A section of the conservation area is expected to be closed to the public for more than a decade following major mine subsidence damage in late 2012.

The mine and NSW government were heavily criticised after it was revealed a creek was filled with grout during a botched subsidence rehabilitation attempt and the damage was kept secret.

‘‘Development work at the mine will be completed by the end of June this year, with all mining to end in mid-2016,’’ Glencore said.

‘‘Consideration had been given to a number of options to extend the mine’s life but a combination of factors, especially coal market and economic conditions, do not support continued operations.’’

News of the closure comes during the inaugural Hunter Coal Festival and in the lead-up to Saturday’s Newcastle Knights’ Voice for Mining family day at Hunter Stadium.

Formal staff briefings will occur this week, but the company said workers had already been informed. 

‘‘We appreciate the impact this will have on our employees and their families, as well as the local communities and businesses supported by West Wallsend’s annual spend of almost $200million across the area,’’ Glencore said.

Last month, it was revealed about 120Glencore jobs were likely to go as the miner cut Australia-wide production by about 15per cent, making it the first major coal company to react to falling prices with a production cut.

Mining began at West Wallsend in 1969 and the mine produces up to 5.5million tonnes of thermal and coking coal annually.

It employs more than 300people, including contractors.

Two new longwall panels were approved at the mine in October last year to replace the coal lost to subsidence on nearby Mount Sugarloaf.

The new panels, 51 and 52, were added into the mine plan at the southern end of the operation.

Changes at the northern end due to mine subsidence cost about 3million tonnes of production, and the new panels will produce about 2.55million tonnes.

Construction, Forestry Mining and Energy Union district president Peter Jordan said his organisation had been contacted about an hour before Glencore put out its media statement.

He said that the union would meet the company on Monday and that West Wallsend supplied domestic power station and export coal.

The mine closure would also spell the end of the Macquarie coal preparation plant, which employed about 15 people.

Another 15 or so truck drivers employed to bring the coal from the mine to the washery were also affected.

Mr Jordan said the mine had  been scheduled to shut in about three years but management were blaming problems with a fault in the workings for the decision to bring the closure forward.

He said West Wallsend was a victim of Glencore’s recent decision to cut its Australian coal production by 15 million tonnes a year.

West Wallsend’s total reserves measured 119million tonnes in 2008, with recoverable reserves of 59 million tonnes.

Glencore’s predecessor, Xstrata, bought the mine in 2002.

It has been producing as much as 4.5million tonnes of coal a year.