Snapchat has been criticised by the Prime Minister for refusing to cooperate with police investigating a paedophile.
The social media company was flagged up by Croydon South MP Chris Philp for failing to co-operate with police in a fresh investigation following the online grooming, rape and murder of 14-year-old Breck Bednar.
Breck was stabbed to death by computer engineer Lewis Daynes in Grays, Essex, in February 2014 in what a judge described as a "sexual and sadistic" killing.
Mr Philp outlined how the paedophile victim's teenage sister Chloe was now receiving "very distressing and disturbing" online messages which may be from Breck's killer, "graphically recounting" her brother's murder.
Speaking during Prime Minster's Questions, he said:
To shouts of "shame" from backbenchers, Mr Philp said Snapchat was claiming police would need to appeal to the United States and "go through a one-year process to get this vital information" as he urged Mrs May to intervene.
"Does the Prime Minister agree this is completely unacceptable?" he asked.
"Does she join me in calling on Snapchat and other social media companies to promptly cooperate with police inquiries and if they do not do so does she agree that legislation is required?" Mrs May paid tribute to Brett's mother for her "brave and powerful" campaigning on the issue of internet grooming and told the Commons the Ministry of Justice was "urgently looking into" the case.
"I agree with him," she said. "We want social media companies to recognise the responsibilities they have and to work with law enforcement agencies.
"It has become increasingly difficult for UK law enforcement to access data containing threats to public safety if data is held or controlled in other countries.
"That's why Government did recently legislate and pass the Crime (Overseas Production Orders) Act, which will give law enforcement agencies the power to obtain electronic data controlled by providers outside the UK, where an international agreement is in place.
"He raises the United States - we expect to establish the first such agreement with the United States."
Security Minister Ben Wallace brought in the Act last month as he sought to tackle a 700% rise in child abuse being reported by tech companies in the last five years.
The Bill allows law enforcement agencies to apply for a UK court order to get stored electronic data from overseas in a bid to counter serious crime and terrorism.
Mr Wallace said the new law would mean child rapists and terrorists could be caught within days, not years.
Treaty plans begun under US President Barack Obama will allow British prosecutors to bypass foreign courts and apply directly to the 99% of tech companies based outside the UK for data relating to child abuse.
The National Crime Agency estimates there are up to 80,000 predators who pose a threat to children, Mr Wallace said, with 1,600 police referrals in 2014 rising to 10,000 referrals in 2017.
Snapchat say they would not be able to verify whether the messages are coming from Lewis Daynes.
They have deleted the account which sent the messages and say they are being as helpful as they can be to police here.
The Ministry of Justice has been investigating but hasn't found evidence to suggest the messages came directly from Lewis from inside prison.