LONDON - Transport minister Jo Johnson announced ambitious plans on Monday for a green revolution on Britain's rail network by phasing out polluting diesel engine trains.

In a keynote speech at the British Museum, Johnson, who is also minister for London, set 2040 as the ambitious goal for the end of diesel trains.

"If that seems like an ambitious goal, I make no apology for that. We're committed to ending sales of petrol and diesel cars by 2040. Why can't the railway aspire to a similar objective?" he said.

Johnson said the average speed of vehicles in the center of London was now only 12.8 km/ph during the day and if it carried on declining, before long it would reach the walking pace of a horse.

Meanwhile, polluting rail emissions have increased by 33 percent since 1990, he said.

He said he wanted to see battery-powered trains between the electric sections of the network, adding: "Or maybe in the future we could see those batteries and diesel engines replaced with hydrogen units."

Johnson said he wanted to see hydrogen train trials on Britain's railway network as soon as possible.

"Hydrogen offers an affordable, and potentially much cleaner, alternative to diesel. So the next generation of trains is just around the corner," he added.

In a strong message to the rail industry, Johnson said: "To speed our journey towards a zero-carbon railway, the government is investing record amounts in public R&D to improve our knowledge base. So today I am calling on the railway to provide a vision for how it will de-carbonize. And I expect the industry to report back by the autumn."