When petroleum giants start investing in electric car technologies, you know the days of fossil fuels are numbered.

BP, the UK's biggest oil and gas company, has acquired Chargemaster, the country's largest electric vehicle charging network.

While BP makes much of its UK revenue from selling petrol and diesel through its 1,200 forecourts, it knows that the era of the combustion engine is coming to an end. By 2040 there are expected to be 12 million electric cars on our roads, up from the 135,000 currently.

Both petrol firms and car makers are switching focus to electric vehicles: Shell bought a charging firm called NewMotion last year, while manufacturers of all types have been investing heavily in electric vehicle production.

At present, 6,500 charge points are owned by Chargemaster, which will be renamed BP Chargemaster. The company also sells home charging points - another aspect of electric vehicle charging that is sure to be highly lucrative in the coming years and decades.

BP is keen to set up charge points in its forecourts so that the growing number of electric vehicle owners have a reason to visit - and so they continue to spend money in forecourt shops as well as on topping up their car.

David Nichols, a BP spokesman, told the BBC: "We have no doubt that the electric vehicle market is growing and will become a significant part of the transport sector in future.

"Chargemaster is a leader in the UK market. We want to learn from them, and eventually, yes, grow the business worldwide."

Chargemaster leads the electric charging industry in the UK, with plans to reduce the time it takes to charge a vehicle. It aims to deliver 100 miles of range in just 10 minutes.

BP is one of seven global oil and gas ‘supermajors’. The Chargemaster deal will help the firm continue to be a key player in the energy sector.