Japanese technology giant Fujitsu has announced plans to cut up to 1,800 jobs in Britain, more than a tenth of its UK workforce .

Fujitsu said the cuts were part of a “transformation programme” aimed at streamlining operations “in order to remain competitive in the market”. It added that the plan, which will see the first workers leave next year, was not linked to the Brexit vote.

The company employs 14,000 people in Britain. The job losses will be spread across Fujitsu’s UK offices, which include London, Belfast, Bracknell, Crewe, Derry, Manchester, Stevenage, Wakefield and Warrington. The firm mainly operates IT systems for big public and private corporations but also provides air conditioning units.

A spokesman said: “It’s clear that we need to reduce the cost base for our customers.” He said the company had started consulting employees on Tuesday and that it was too early to say where the cuts would be made.

Most of the redundancies are likely to come next year but they could stretch into 2018. Fujitsu also plans up to 400 job reductions in Finland, where it employs 2,500 people.

Unite, Britain’s biggest trade union, described the job losses as a “hammer blow” to Fujitsu employees and the wider UK economy.

Ian Tonks, a Unite national officer, said: “It is not good news for the UK economy as the company says that it intends to offshore many of these jobs, with increased automation also responsible for job losses.

“Fujtsu’s main UK subsidiary made £85.6m profit last year and we see no reason for these job losses. Unite will be doing its utmost to fight for these jobs, as well as giving our members maximum support at this very worrying time.”

The news came as Fujitsu workers in Manchester voted in an industrial action ballot over pay, pensions and job security.

Unite claims the company has been cutting pay rates for years despite healthy profits, and said that it had failed to tackle a significant gender pay gap. The strike ballot result is expected next Wednesday.

The company has also given notice to terminate its UK works council, Fujitsu Voice, from January 2017. The union is fighting the move.

Fujitsu employs 1,500 people in Bracknell, 701 in Northern Ireland, 693 in Stevenage, 636 in Manchester, 572 in London and 511 in Warrington.

The firm said in a statement: “Fujitsu is planning a transformation programme that will enable it to better support customers in the era of digital transformation. The company today advised its employee representative forum of plans to restructure the organisation in order to provide better service and respond more quickly to customer needs.

“As part of the programme, Fujitsu plans to streamline operations in order to remain competitive in the market. Proposed measures include changes which would result in a reduction of up to 1,800 jobs in the UK. All affected employees will be offered guidance and support and Fujitsu is establishing a consultation process with elected employee representatives.”

The IT company confirmed a few days ago that it was in talks to sell its computer business to Chinese tech company Lenovo. Lenovo has become one of the biggest players in the computer market alongside US rival HP, after acquiring IBM’s PC business in 2005.

Tatsuya Tanaka, Fujitsu’s president, had warned ahead of the EU referendum that a vote to leave the EU would be a “huge negative” for the IT firm’s business in the UK.

Other Japanese companies such as Nissan and Hitachi have expressed strong concerns over the UK’s departure from the EU and the prospect of higher tariffs.

Carlos Ghosn, Nissan’s chief executive, recently sounded a warning over potential new investments in the UK’s biggest car factory in Sunderland and demanded compensation from the government for any tariffs that may be imposed after Brexit. Nissan is due to decide early next year on where to build its next Qashqai sport utility vehicle.

Julie Elliott, the Labour MP for Sunderland Central, warned on Tuesday that the city and wider region faced the threat of tens of thousands of job losses – “on a scale not seen since the closure of the shipyards and coal mines”. She urged Theresa May to give assurances to the Japanese carmaker over trade tariffs.