A proposed blanket ban on social media use for under-16s faces potential reversal next week despite being previously backed by the House of Lords.

The government is instead pushing for a more adaptable power, allowing for the blocking of children from “specified internet services” rather than a strict age limit for under-16s.

Should MPs approve this amendment within the Children’s Wellbeing and Schools Bill, ministers would acquire new authority to impose social media curfews or restrict screen time for young people.

Crucially, while Lords sought a direct ban on user-to-user platforms, the revised proposal grants ministers discretion over the specific measures to be implemented.

John Nash, who steered the ban in law through the upper House, described this as a “blank cheque”.

The government launched an online safety consultation on Monday, which explores several themes including whether social media platforms should come with a minimum age requirement, and whether platforms should switch off addictive features such as autoplay.

Lord Nash told the Press Association: “The government’s amendment confirms that they remain firmly on the fence on how best to protect children.

“In fact, it is patently clear that raising the age limit to 16 for harmful social media platforms is far from their preferred option.

“MPs must choose on Monday whether to act now and raise the age limit for harmful social media to 16, or vote for the government’s amendment, which is in effect a blank cheque, committing only to further delay while their consultation runs its course.

“That consultation is simply yet another opportunity for Big Tech to mobilise their lobbyists and water down any prospective measures before they reach the statute book.”

Lord Nash, a Conservative former minister, added that he has backed a letter-writing campaign by raisetheage.org.uk ahead of Monday’s Commons debate on the Bill.

He said his proposal, which peers backed in January by 261 votes to 150 – majority 111, was “the only legislative vehicle on the table that will force the government to raise the age limit for harmful social media platforms”.

He said MPs should back his proposal instead of the government’s “without hesitating”.

Launching the consultation earlier this week, technology secretary Liz Kendall said: “We know parents everywhere are grappling with how much screen time their children should have, when they should give them a phone, what they are seeing online, and the impact all of this is having.”

She urged children and parents to take part in the government’s consultation.

“Together, we will create a digital world that gives young people the childhood they deserve and prepares them for the future,” she said.