London: World Wide Web inventor Sir Tim Berners-Lee says the impact of fake news is increasingly concerning and has unveiled plans to tackle "unethical" political advertising and the harvesting of data.

The British computer scientist said on Sunday, exactly 28 years after his invention, the three new trends have become alarming in the last 12 months.

In an open letter published in the UK, Sir Tim, 61, said misuse of data has created a "chilling effect on free speech" and warned of "internet blind spots" that are corrupting democracy.

One problem, he wrote, is that most people find their news and information through a "handful" of social media sites and search engines, which are paid whenever someone clicks a link.

"The net result is that these sites show us content they think we'll click on, meaning that misinformation or fake news, which is surprising, shocking or designed to appeal to our biases, can spread like wildfire," he added.

"And through the use of data science and armies of bots, those with bad intentions can game the system to spread misinformation for financial or political gain."

Companies and governments are using widespread data collection to "trample on our rights", leading to bloggers being arrested and killed by repressive regimes, Sir Tim said.

"But even in countries where we believe governments have citizens' best interests at heart, watching everyone all the time is simply going too far," he wrote.

"It creates a chilling effect on free speech and stops the web from being used as a space to explore important topics, such as sensitive health issues, sexuality or religion."

Sir Tim also criticised politicians for targeting voters using sophisticated algorithms to tailor messages to ones they will approve of.

"Targeted advertising allows a campaign to say completely different, possibly conflicting things to different groups. Is that democratic?" he said.

Oxford-educated Sir Tim, who submitted his original proposal for the web on March 12 1989, urged people to call for greater protection laws and that Google and Facebook increase their efforts to tackle fake news.

The "internet blind spot" in political campaigning must be closed while alternative revenue streams must be explored so data is not sold so indiscriminately, he said.

He plans for the Web Foundation, which he founded in 2009, to work on the issues in a five-year strategy.

PA