Facebook, Apple, Microsoft and Google are to give secret evidence to the independent inquiry into child sexual abuse (IICSA) as it examines the growing problem of online exploitation.

Representatives of the four global tech companies will make part of their submissions in closed sessions of the inquiry, which is being held in Southwark, south London.

At the opening of a new strand of IICSA hearings, William Chapman, a barrister representing grooming and abuse victims, called on the major technology companies to do far more to “curb the modern scourge” of sex crimes carried out via the internet.

Chapman, acting for the law firm Switalskis, also called for the Criminal Injuries Compensation Authority to change its rules so that victims of online abuse would be eligible for payments in future.

“In the real world,” he said, “a playground created for children would have to be safe … It would not be sufficient to put up a notice which said: ‘Enter at your own risk.’” That, however, mirrored the state of the internet today, he said.

He said Bing, the second most popular search engine after Google, had recently provided links to child pornography sites to those entering even common search terms.

He said the founders of the largest tech companies portrayed themselves as the heroes of the technological revolution but had legendary wealth and “notorious tax arrangements”.

“Is it really beyond the wealth and wit of these companies to prevent and detect child sexual abuse on their platforms or is there something incompatible with their commercial objectives and culture that makes them bridle at the necessary steps to curb the modern scourge?”

Chapman said the spread of end-to-end encryption would make it even harder to eradicate child sexual exploitation online in future. The solicitor represents three victims who were abused as young children, identified only as A1, A2 and A3.

A1 and A2 are a brother and sister who were groomed online when they were aged 12 and 13 by Anthony O’Connor, 57, who is serving a 14-year prison sentence for his offending. He forced the young boy to touch his sister sexually and suggested they have intercourse as he watched.

A3, who was 14 when the abuse began, was groomed online and offline by the B&B owner Lawrence Glynn when she went to work for him. Glynn was convicted and imprisoned for two years after sexually assaulting her.

A3, who is now in her early 20s, recalled her experience of being pursued by the man and told the inquiry of her sense of being “absolutely violated” by the abuse.

She said Glynn had always been a strange man, passing comments about her clothes or legs. He tried to get her and another girl to change into uniform skirts. “He said he wanted pictures for the B&B’s website,” she said. He took pictures of them sitting on the stairs revealing their underwear.

At one stage he put a hidden camera in a bathroom to take pictures of her and later sexually assaulted her. She said she was left feeling “absolutely violated”.

A3 said that as a result of the abuse she could not sleep in her house on her own and had nightmares about what had happened. She is worried about whether the pictures Glynn took have been circulated on the internet.

“You don’t know if people have sold images of yourself,” she told the inquiry. “It’s an awful thing to think that paedophiles could look online and find whatever they want. It’s scary.

“There needs to be more education in schools. You can’t just give children one lesson about online safety. So many people lie online about who they are. It’s ruining kids’ lives.”

Earlier, Jacqueline Carey, counsel to the inquiry, told the hearing that the amount of time that 12- to 15-year-olds spent online continued to rise. In 2016, Ofcom reported that they spent an average of 20 hours and six minutes looking at social media and the internet a week. By 2018, the regulator’s figures showed it had gone up to 20.5 hours a week. About 83% of 12- to 15-year-olds have their own smartphone.

In 2018, the Internet Watch Foundation found criminal child sexual abuse content in more than 105,000 reports made to them – a 32% increase from 2017. Carey said law enforcement agencies believed there could be as many as 100,000 people in the UK involved in the downloading and sharing of indecent imagery.

But Peter Alcock, counsel for the IWF, later told the inquiry the number of images detected online with child sexual abuse content had fallen in the UK as a proportion of overall internet content from about 18% in 1996 to less than 1% by 2003 and had continued falling since then. Last year, only 41 web pages were reported and removed in the UK.

Parts of the tech companies’ evidence sessions are being held behind closed doors, according to the inquiry, so that they can answer questions about documents covered by previous restriction orders.

The hearing continues.