A new high-speed Eurostar e320 train leaves the Channel Tunnel in Coquelles, near Calais, northern France, October 20, 2015. [Photo/Agencies]

LONDON - Train managers on the Eurostar line linking Britain to continental Europe will strike for a total of seven days in August because of a long-running dispute over anti-social working hours, Britain's RMT rail union said on Wednesday.

The RMT said the strike action would take place in two blocks over two weekends, from 2301 GMT on Aug. 12 to 2259 GMT on Aug. 15, and from 2301 GMT on Aug. 27 to 2259 GMT on Aug. 29.

The dispute involves 80 train managers who are RMT members. The union said 95 percent of them had backed the strike action in a ballot.

Eurostar said it would have to make small changes to its timetable on those days to ensure all passengers booked to travel could do so. It may need to cancel one or two trains but passengers would be able to travel on later ones, the company said.

"Our focus has been seeking a joint resolution, naturally, while planning to provide a good service for our customers," a Eurostar spokeswoman said.

The RMT said the dispute with management centred on what it called Eurostar's failure to honor an agreement from 2008 which sought to ensure that train managers could expect a good work-life balance in terms of unsocial hours and duty rosters.

"Our train manager members at Eurostar have a heavy commitment to shift work and unsocial hours and are sick and tired of the company's failure to honor agreements," RMT General Secretary Mick Cash said in a statement.

"Our members have every right to have a fair work-life balance that fulfils the operational needs of the company while guaranteeing quality time off for friends and family."

Eurostar, which is majority-owned by the French state rail operator SNCF, said efforts to resolve the dispute were ongoing.

RMT spokesman Geoff Martin said talks had been suspended but he expected the strike announcement to "focus minds" and bring management back to the negotiating table.

He said the RMT expected the strike to have a major impact, adding that train managers had crucial security responsibilities and could not easily be replaced by agency workers.