Demand for online video websites such as YouTube and the BBC's iPlayer are putting the internet under so much strain it may collapse within two years, experts have revealed.

They claim that unless billions of pounds is spent on upgrading the copper wires, which underpin parts of the web's infrastructure, an internet meltdown is highly likely.

Larry Irving, co-chairman of the Internet Innovation Alliance, a US industry group lobbying for universal improvements in the web's network, told The Telegraph: "Our streets in cities like London or New York were designed for a certain amount of traffic. There are times of the day when you can get around and times when there is congestion. London does not shut down, it carries on, but everything slows down. The internet is something like that.”

Irving said that the copper wires were only intended to carry voice calls. The surge in transfers of video-related data means the wires are at risk of becoming overloaded, especially since internet traffic is increasing at a dramatic rate.

Online monitoring firm Hitwise has recorded a 178 percent increase in visitors to video websites in the past year.

In a bid to combat a web meltdown, internet service providers (ISPs) are putting in place plans to swap the copper wires for high-speed fibre optic cables. BT's £10bn scheme starts this month and should be complete by 2012. However, there are concerns that it won't be able to cope with demand.

Anthony Walker, chief executive of Britain's Broadband Stakeholder Group, said: "There are big investment challenges ahead. Replacing copper with fibre optic, taking it closer to the consumer – we're talking about billions of pounds over almost a decade."