LONDON — Workers on Eurostar trains that operate across the English Channel are planning seven days of strikes over two weekends in August – a peak summer tourist time.

The Rail, Maritime and Transport union says its members will stop work for four days starting Friday, Aug. 12. A second stoppage is planned for three days starting Aug. 27, which is the start of a bank holiday long weekend for the British.

It wasn’t immediately clear what impact the strike would have on Eurostar’s operations.

The strike comes amid a dispute over what the RMT union says is “the work/life balance of safety-critical train managers.”

The union claimed Wednesday that Eurostar has failed to honour a 2008 agreement to reduce the number of unsocial hours that the staff is required to work.