About 20% of boys, who go online, have reportedly accessed porn websites via PCs, according to the latest research.
The latest Authority for Television On Demand (ATVOD) report found that about 44,000 primary school children, and 200,000 below the age of sixteen accessed adult content in December 2013.
ATVOD chair Ruth Evans said:"The Government needs to act urgently with a range of measures to protect children from this content.
"Key among them is legislation to make it possible for the UK payments industry to prevent funds flowing from this country to websites which allow children to access hardcore pornography."
The report found that about 23 of the 25 adult websites accessed from the UK are unregulated and allow free, open access to hardcore porn to visitors of any age.
It found that one in four Brits accessed an adult website at least once from a PC or laptop in December, with average time spent on every site ranging 15 minutes per visit and to two and a half hours over 10 visits.
ATVOD CEO Peter Johnson said:"This makes ‘following the money’ the most compelling strategy for securing enhanced child protection."
The UK government has already forced internet service providers to deploy porn filters that automatically block adult material.
