A US judge has ordered Starbucks to reinstate seven employees at a cafe in Memphis, Tennessee who were allegedly fired for supporting a union campaign, as the coffee chain struggles to halt pending nationwide union elections.

Sheryl Lipman, the district judge in the city, said the US National Labor Relations Board had provided enough evidence that the dismissals earlier this year were motivated by anti-union feeling. Lipman granted the order pending the outcome of an administrative case before the board.

The Memphis store is one of nearly 220 Starbucks cafes in the US to unionise over the last year. Workers at 46 locations have voted against unionising, and dozens of other elections are pending.

Starbucks said in a statement on Thursday it disagreed with the ruling and planned to appeal. The company said the workers were fired for violating company safety policies and that it respected the unionisation process.

In a statement, NLRB general counsel Jennifer Abruzzo called the decision “a crucial step in ensuring that these workers, and all Starbucks workers, can freely exercise their right to join together to improve their working conditions and form a union”.

In May, the NLRB made the rare move of seeking an order in a federal court in the Memphis case, as claims that the workers were unlawfully fired were heard before an administrative judge.

The board is considering scores of other complaints alleging Starbucks interfered with workers’ organising rights, including by closing stores and dismissing or disciplining union supporters.

In a letter to NLRB officials on Monday, Starbucks accused board staff of improperly aiding the union and asked for elections to be suspended nationwide pending the outcome of an investigation.