The UK’s age-verification system for online pornography will be delayed for around six months because the government failed to inform the EU of its proposals, the culture secretary has said.

The already delayed policy, which will require all adult internet users wanting to watch legal pornography to prove they are over 18 by providing some form of identification, was due to come into force on 15 July.

However, the culture secretary, Jeremy Wright, told the House of Commons, that would not happen, because of a failure to comply with European law in how statutory instruments are passed.

“In autumn last year, we laid three instruments before the house,” Wright told the Commons. “One of them sets out standards that companies need to comply with. This should have been notified to the European commission, and it was not. This will result in a delay in the region of six months.”

The delay, first reported by Sky News, is likely see the issue of age verification fall under the responsibility of the next prime minister.

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Wright emphasised that the delay did not mean the government was backing down from its policy. “There are also those who do not want these measures to be brought in,” he said, “but let me be clear, although this is an apology for the delay, it is not a change in policy. Age verification needs to happen, and in the interest of the needs of children, it must.”

Labour’s Cat Smith, responding, said the announcement was “proof that an important policy issue has descended into utter shambles”.

Citing a Guardian report showing that fake profiles could circumvent blocks in minutes, Smith suggested the delay showed that the government could not even be sure the blocks would work when, or if, they were eventually introduced. “When this legislation was going through this place Labour raised serious concerns about whether the verification process was viable … This delay shows we were right to be concerned.”

The age block was due to be one of the first of its kind anywhere in the democratic world. Websites that refused to implement the checks faced being blocked by UK internet service providers or having their access to payment services withdrawn.

However, the proposed system came under repeated attack from privacy campaigners who raised fears that – despite the reassurances of age-verification sites – it would be possible to connect an individual’s browsing habits to their identity, which could then be exposed in a data leak.

Jim Killock of Open Rights Group, which has campaigned against the law, warned last week that the data protection standards under the proposed system were “pointless, misleading and potentially dangerous as advice to consumers seeking safe products”.

Responsibility for checking ages under the system was given to private companies, who would be overseen by the British Board of Film Classification – an organisation which has limited experience of technical internet regulation.

The government was also forced to exempt large social media sites from the ban owing to fears that a strict implementation would result in the likes of Twitter, Reddit, and Imgur being blocked for adult content.

The law’s supporters say it is designed to stop young children accidentally stumbling across pornographic content while browsing the internet and accept it will not be an effective ban on older, more persistent teenagers.

The delay to one of the government’s main internet safety policies shows the enormous challenges associated with attempting to regulate the internet. It also raises questions as to how a similar age-verification system for all mainstream websites – as proposed by the information commissioner’s office – could be implemented.

The delay is damaging to many British age-verification businesses who invested substantial sums of money in developing systems to provide the tools required to check internet users’ identities. They were relying on the launch going well in order to sell their products around the world and make the UK a hub for global age-verification systems, with many backed by small investors who could lose out in the event of a lengthy delay.

Age verification was first proposed in the run-up to the 2015 general election by Sajid Javid, when he was culture secretary in the coalition government.