Rail passengers in northern England, have been promised more seats, more services and new trains under franchise plans announced by the Government - but the outdated Pacers will not be replaced until 2020 at the earliest.

Outlined by Deputy Prime Minister Nick Clegg and Transport Secretary Patrick McLoughlin, the improvement plans cover the Northern, which serves the Bradford region, and TransPennine franchises, which both serve which will be re-let next year.

Companies already short-listed in the competition to run the two franchises will be required to replace outdated Pacertrains and introduce new trains.

They will also have to tackle overcrowding, invest in stations, add more than 200 new train services every day across both franchises and accommodate more than 19,000 extra commuters in Manchester during the morning rush hour.

In all, the successful bidders will have to provide more than one third more capacity on routes covered by the two franchises as well as introduce free wi-fi.

Today, announcing the invitations to tender, Mr McLoughlin and Deputy Prime Minister Nick Clegg said the requirements successful bidders will have to meet meant huge improvements for northern England train travellers.

They said there would be more services, more seats and improved facilities, with Mr Clegg describing it as "an historic moment for the North".

But rail unions dubbed the announcement "a pre-election stunt", with the RMT saying the plans would "condemn passengers to poor-quality, unsafe and de-staffed services".

The new nine-year Northern franchise starts on April 1 2016 and on the same day a new seven-year TPE franchise will start.

The Northern franchise operates local, commuter and rural services throughout the region, and a number of long-distance services linking major towns and cities such as Leeds, Sheffield, Nottingham, York, Manchester, Bradford, Preston and Blackpool.

The TransPeninne Express franchise provides longer-distance intercity-type services, connecting the major cities of Newcastle, Leeds, Sheffield, Manchester, Hull, Liverpool, Edinburgh and Glasgow, as well as Manchester Airport.

Companies shortlisted to run the new franchises were announced last August. Competing for Northern are Arriva, Govia and Northern, while on the shortlist for TPE are FirstGroup, Keolis/Go Ahead and Stagecoach.

Mr Clegg said: "This is an historic moment for the North. Improving rail links in the region has been much anticipated. These old trains have been rattling across rails in the North for over 30 years - a constant source of complaint which have held the region back.

"Today's plans include a new fleet of trains and improved services that will better connect our great Northern towns and cities. Modernising rail in the North will encourage business, boost tourism and give commuters the journey they deserve; one that is fit for a 21st century metropolis."

Transport Secretary Patrick McLoughlin said: "This is great news for passengers across the north, who will finally get a rail service that matches up to the booming economy in this region. That means more seats, more services and a brand new fleet of modern trains.

"Unlike the last Northern franchise in 2004, which included limited plans to invest in services or meet demand, this deal will maintain investment and grow to fit the needs of passengers for years to come.

"Together with the £1 billion investment we are making to improve the region's railways and our plans to link east and west through HS3, our railways are making the region an economic powerhouse."

The Northern franchise operates local, commuter and rural services throughout the region, and a number of long-distance services linking major cities such as Leeds, Sheffield, Nottingham, York, Manchester, Bradford, Preston and Blackpool.

The TransPeninne Express (TPE) franchise provides longer-distance intercity-type services, connecting the major cities of Newcastle, Leeds, Sheffield, Manchester, Hull, Liverpool, Edinburgh and Glasgow, as well as Manchester Airport.

Companies shortlisted to run the new franchises were announced in August 2014. Competing for Northern are Arriva, Govia and Northern, while on the shortlist for TPE are FirstGroup, Keolis/Go Ahead and Stagecoach.

James MacColl, head of campaigns at the Campaign for Better Transport, said: "This is a step toward the modern, high-capacity rail network northern cities need to connect them.

"Much of the exisitng network has be starved of investment, leaving poor facilities, sparse timetables and trains that should have been scrapped a decade ago."

And even this phasing out in five years' time has been questioned on value-for-money grounds by the Department for Transport's permanent secretary Philip Rutnam.

Earlier this week Mr Rutnam wrote to Transport Secretary Patrick McLoughlin saying there would be large costs involved in replacing the Pacers with new trains, as well as "relatively few benefits".

Mr Rutnam said that investing in new trains would bring "no significant improvements in journey time, frequency or new services".

But Mr McLoughlin wrote back ordering Mr Rutnam to proceed with approving the invitations to tender for the new Northern and TransPennine Express (TPE) franchises, whose terms include the 2020 replacement of the Pacers.

Mr McLoughlin said there were "wider issues to consider" and described the Pacers as uncomfortable and of low-quality.