Secondary schools will start opening up to more students from 15 June, the prime minister said today.

But only Years 10 and 12 will come back from that date. And attendance among them will be limited to only “around a quarter of students in at any point”.

Prime minister Boris Johnson’s announcement tonight means the government has stepped back from its original plan for secondaries “to begin some face-to-face support with Year 10 and 12 pupils” from Monday 1 June.

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Tonight, Mr Johnson said the government intended “from 15 June to provide some contact for Year 10 and Year 12 students to help them prepare for exams next year with up to a quarter of these students in at any point”.

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He added: “By opening schools to more pupils in this limited way, we’re taking a deliberately cautious approach.”

The government said today’s announcement came after consultation with schools, teachers and unions, led by education secretary Gavin Williamson.

Mr Williamson said: “This has been a difficult time for the entire country. Education and childcare staff have stepped up to the challenge, making sure children and young people have continued to be supported throughout the past 10 weeks.

“Our priority is the education and welfare of all children and young people across the country.” That is why, he said, the government wants to start a phased wider opening of nurseries, schools and colleges informed by the best possible scientific and medical advice.

“We will continue to work with the sector to support them to prepare for wider opening and ensure all children and young people can continue to receive the best care, education and training possible.”

The Association of School and College Leaders welcomed “the decision to push back bringing in Year 10 and 12 students to 15 June and the clarification about the maximum number of students at any one time”.

“However, we have to say that the government has not done a good job in building confidence in its plans,” the association’s general secretary, Geoff Barton, added.

“It has not communicated the rationale for its chosen approach well.”