Aslef’s lead negotiator has said the union is putting “members first” in a “toxic situation” after announcing a fresh series of strikes.

Train drivers working for LNER – which runs the passenger service on the East Coast main line between London and Edinburgh – will walk out on weekends from the end of August in a dispute about working agreements.

The dispute is separate from the long-running row over pay, which looks likely to be resolved after a new offer this week from the Government.

Lead negotiator Nigel Roebuck told Times Radio: “We work within agreements, we jointly sign up to agreements. We make agreements, we don’t break them.

“When you get to the strike action decision, it’s because all else has failed. You can only try for so long.”

He praised Transport Secretary Louise Haigh for being “the adult in the room” during pay negotiations, but said LNER had “consistently blocked” attempts to settle the latest dispute.

“We put our members first and our members’ mandate is on a separate issue which has been ongoing for two years,” he said. “This dispute is not connected to the pay, it’s about upgrading of our agreements.

“We’ve now got a toxic situation, we’ve got morale in the gutter among our members.

“Our members are saying they want to work to their agreements, they want respect and dignity and we need to move forward.”

The planned strikes will cover a total of 22 days covering every Saturday and Sunday from September 1 to November 10.

An LNER spokesperson said: “Our priority focus will be on minimising disruption to customers during the forthcoming Aslef strikes, which sadly will continue to cause disruption and delays.

“We are surprised and disappointed to hear this news following recent constructive conversations.

“We will continue to work with Aslef to find a way to end this long running dispute which only damages the rail industry.”