Another rail company is to be affected by a train drivers’ strike, threatening huge disruption to services.

Aslef announced on Tuesday that its members in 12 train operating companies will walk out on October 1 and 5 in a long-running dispute over pay.

The union said drivers will also strike at East Midlands Railway on October 5 after members voted for industrial action earlier this week.

The strikes will disrupt travel for delegates and visitors to the Conservative party conference in Birmingham.

Services are likely to be affected on October 2, the day of the London Marathon.

The Rail, Maritime and Transport union has also announced a strike for October 1 among its members at Network Rail and 14 train companies.

Mick Whelan, Aslef’s general secretary, said: “We don’t want to go on strike – withdrawing your labour, although a fundamental human right, is always a last resort for this trade union – but the train companies have been determined to force our hand.

“They are telling train drivers to take a real terms pay cut. With inflation now running at 12.3% – and set, it is said, to go higher – these companies are saying that drivers should be prepared to work just as hard, for just as long, but for considerably less.

“The companies with whom we are in dispute have not offered us a penny. It is outrageous that they expect us to put up with a real terms pay cut for a third year in a row.”

Aslef members at 13 companies – Avanti West Coast; Chiltern Railways; CrossCountry; East Midlands Railway; Greater Anglia; Great Western Railway; Hull Trains; LNER; London Overground; Northern Trains; Southeastern; TransPennine Express; and West Midlands Trains – will strike on October 1 and 5, while drivers at East Midlands Railway will walk out on October 5.

Aslef said it has concluded pay deals with 11 rail and freight companies this year including Eurostar, GB Railfreight, Merseyrail, MTR Elizabeth line and ScotRail.

A Rail Delivery Group spokesperson said: “These strikes will once again hugely inconvenience the very passengers the industry needs to support its recovery from the ongoing impact of the pandemic.

“They range from those left out of pocket because they can’t get to work, to people missing vital appointments and to thousands of London marathon participants, who, after months of training, will have their journeys to London disrupted at the weekend.

“The strikes are not in the long-term interests of rail workers or building a sustainable rail industry. We want to give our people a pay rise, but without the reforms we are proposing, we simply cannot deliver pay increases.

“Revenue is still around 80% of pre-pandemic levels; no business can survive that scale of upheaval without implementing change.

“The actions of union leaders have very real consequences: every strike day takes more money out of their members’ pockets.

“We want to see the industry and its people thrive – we are asking the unions’ leadership to do the right thing, call off these damaging strikes and work with us to make that happen.”

The Transport Salaried Staffs Association announced it will ballot hundreds of its members at Govia Thameslink Railway (GTR) over possible industrial action, including strikes.

The union represents workers including platform and ticket office staff, train crew, engineers and management.

General secretary Manuel Cortes said: “This is a clear signal to GTR that our members are not willing to be pushed around in the face of an escalating Tory cost-of-living crisis and a Government which wants to slash jobs on the railways.

“I want to encourage our members to vote yes both to strike action and action short of a strike because we know we are in a fight for the future of our railways.

“We have already seen a strong set of ballot results elsewhere in rail companies our union represents and we are ready to take strike action again in the coming weeks.

“Ministers and bosses at GTR would do well to get real and address our concerns now, so that further disruption does not take place.

“If not, there is likely to be crippling action on one of the main train networks in and out of London and beyond in the near future.”

Angie Doll, chief operating officer at GTR, said: “Our focus remains on encouraging all unions to continue to work with the industry to seek a resolution that will ensure the long-term sustainability of the railway.”