rail
David Cameron said the policy could save commuters hundreds of poundsGetty

David Cameron has pledged to freeze regulated train fares for five years if the Conservatives are voted into power after the general election.

The Prime Minister has said extending the Retail Price Index cap on ticket prices until 2020 could save rail season-ticket an average of £400.

The cap imposes restrictions on how much rail companies can increase fares by as well as the "flex" option which results in tickets prices increasing higher than the rate of inflation.

Earlier this year, the average rail fare across England and Wales increased by 2.2%, with regulated fares, including season tickets, rising by 2.5%.

The promise arrives after the Tories fell behind to Labour in three separate election polls after members of the party launched personal attacks against Ed Miliband as part of their campaign.

In one poll, from Panelbase, Labour were on 37%, six points ahead of the Conservatives. Elsewhere, a TNS poll put Labour on 33% compared to the Tories on 30% and Survation put Labour on 35%, up from 33% in April, while the Conservatives fell one point to 31%.

The Prime Minister said: "The cost of commuting is one of the biggest household bills that hardworking families face and it is something we are determined to bear down on.

"Because of the difficult decisions that we have taken to repair the economy, we have been able to hold down commuter fares for the past two years.

"Because of the difficult decisions that we have taken to repair the economy, we have been able to hold down commuter fares for the past two years.

"If elected in May, we would freeze them in real terms for the next five. Under Labour, commuters were hit with above-inflation rises year after year. And if they got in again, the chaos they would wreak on the economy would ensure that it happened all over again."

Cameron said the current policy meant commuters are already paying £75 less than they would be if the cap had not been introduced.

However, union leaders have described the promise as a "stunt" and once again call for the railways to be re-nationalised.

Mick Cash, leader of the Rail, Maritime and Transport union, said: "This latest stunt would still mean annual fare increases that would institutionalise the harsh reality that the British passenger pays the highest fares in Europe to travel on rammed out and unreliable trains.

"The only solution is to end the rip off of rail privatisation which would allow us to free up the hundreds of millions of pounds drained off in profits to invest in services and cut fares."