Almost half of the UK's National Cycle Network is in a poor or very poor condition, according to new research.

High-speed vehicles, too many barriers and unstable surfaces were among the faults found on the 16,500-mile network of paths and on-road cycling and walking routes.

Independent analysis commissioned by transport charity Sustrans, which gained funding to develop the network in 1995, classified the condition of 42% of it as "very poor" and 4% as "poor".

That means 7,596 miles are unsuitable for a 12-year-old to use safely, the report warned.

One respondent to a survey of 6,000 people described their local path as a "mud bath" which means they cannot use it when cycling to work as they would get too dirty.

Another called for the network to have better signage and more segregation to "make it feel safer".

Sustrans has unveiled recommendations for a UK-wide overhaul of the network to open up walking and cycling to more people, including children and anyone with impaired mobility.

The charity wants more routes to be traffic-free, but where this is not viable it believes the "character" of minor roads should be changed by reducing speed limits.

Sections on major roads should be diverted off-road, segregated from traffic or even removed from the network, according to the report.

Sustrans' aims to develop more than 50 improvement projects to the routes by 2023.

Its ambition is for a further 5,000 miles of the network to be free of traffic by 2040 and every mile classified as "good" or "very good".

The charity estimates this would cost £2.8 billion and would lead to the number of users rising from 4.4 million in 2017 to 8.4 million.

Sustrans' chief executive Xavier Brice said: "The National Cycle Network is a well-loved, well-used asset that's enjoyed by millions of people across the UK every day.

"We want to build on its success and make the network safer and more accessible for everyone, not just for people who currently use it.

"Our Paths for Everyone report lays out an ambitious vision to make the network traffic-free and safe for a 12-year-old to use on their own.

"However, historic problems such as poor surfaces, incomplete signage or barriers mean that for people with mobility issues or those of us who are less physically active, there may as well be a 'no entry' sign on their local path."

Cycling and Walking Minster Jesse Norman said: "The National Cycle Network is a familiar sight for many, and a great asset for cyclists and walkers across the country.

"This report shows that more needs to be done to make it fully accessible, and that's why earlier this year the Government dedicated £1 million to support initial work repairing and upgrading sections of this popular network."