Rail services on some of the busiest routes in the country will be disrupted this week because of a five-day strike in the long-running dispute over guards on trains.

Members of the Rail, Maritime and Transport union on South Western Railway will walk out from Tuesday, hitting services including busy commuter trains into London Waterloo.

Services will be cancelled or disrupted and the stoppage coincides with the Royal Ascot horse race meeting.

Industrial action was suspended in February when it appeared a resolution was in sight. But the union is renewing strikes after accusing the company of "dragging its heels" in protracted talks over the past few months.

The RMT said SWR company was not prepared to give assurances that its new operational model won't move to driver controlled operation, which sparked fears of a "stitch up".

According to the RMT, the train company pledged in February that "each passenger train shall operate with a guard with safety critical competencies", which led the union to suspend industrial action.

Union officials said since then it has been "stalemate", accusing the company of "rowing back" on its public pledges.

RMT general secretary Mick Cash said: "Our members have been left with no choice but to go ahead with strike action tomorrow. They are angry and frustrated that despite suspending action in good faith, and entering into talks in a positive and constructive manner, South Western Railway have dragged their heels and failed to bolt down an agreement that matches up to our expectations on the guard guarantee.

"Worse than that, the company have refused to give assurances on the future operational role of the guard fuelling fears amongst our members of a stitch up.

"That situation has been compounded by an insistence that future operational models will be governed by the protection of company profits and not the safety of the travelling public.

"For more than three months we have sought to negotiate a conclusion to this dispute and it is wholly down to the management side that the core issue of the safety critical competencies and the role of the guard has not been signed off. It is because of that crucial failure by SWR that we have had no option but to lift the suspension and move back into strike action."

A South Western Railway spokesman said: "It's very disappointing that despite having had dates in the diary for what we hoped would be further constructive talks, the RMT union decided to call disruptive strike action over the course of five days."

The company said it met with the union last week and agreed to arrange new dates to continue those talks.

"However, they seem insistent on going ahead with their unnecessary strike which will impact our customers and colleagues alike. Clearly, they have decided to target popular events such as Royal Ascot with this cynical action which is driven by internal RMT politics.

"The RMT has always said it wanted us to keep the guard on every train which is what we have offered as part of a framework agreement.

"We want to move the conversation on to how we operate our new trains and take advantage of the new technology on board to benefit our customers.

"We remain committed to finding a solution that will help us build a better railway for everyone. We will do everything we can to keep customers moving during these strikes but would like to apologise for the disruption this unnecessary action will cause.

"Passengers are strongly advised to plan their travel in advance as services are likely to be busier than usual because of the strike action.

"Rail replacement services and ticket acceptance on other bus and rail networks have been organised where possible, whilst fans attending events at Twickenham, Hampton Court, Royal Ascot, and elsewhere, are advised to allow extra time for their travel.

"Customers will be able to see amendments to their train services, as currently published on our website.

"Further information on additional main line peak-time services - over and above the amended timetable - will be announced in due course."