The ban on children playing together outdoors in England must be lifted as it is discriminatory and potentially unlawful, lawyers and children’s groups have said. In a letter to Boris Johnson in the week that schools were allowed to reopen, family groups reported signs of mental distress and poor health among young children who have missed playing and socialising. Since 6 January across England, and last year in places under tier 3 rules, the law has stated that only two individuals can meet from different households. Under-fives are exempt but campaigners say that children aged five to 11, who are not old enough to meet a friend alone, have been severely affected by the rules. Jennifer Twite, of Just for Kids Law, said the rules were challengeable under the Equality Act 2010 and the European convention on human rights. “The current guidance in England unfairly discriminates against children and disproportionately impacts single parents. Under the one-to-one rule, adults and older children have been able to meet a friend for exercise if they can do so alone but this leaves children who are over five unable to see anyone. This leaves single parents, who are more likely to be women, also unable to take advantage of the rule because they can’t bring their children if they meet another adult.” Government guidelines have also stressed that playgrounds, while open, must not be used for socialising. In a letter to the prime minister, the groups Just for Kids Law, Playing Out and Play England point to the rules in Scotland that have always allowed under-12s to mix with friends outdoors. On Monday, Nicola Sturgeon relaxed rules specifically for teenagers so they can meet in groups of four. Ingrid Skeels is co-director of the group Playing Out in Bristol. She said the rules needed to be changed urgently, not at the end of March. “Every day counts and the current ban gives a wrong and fearful message that outdoor play and socialising isn’t safe. “ She said the group had heard from many parents who have been too afraid of being fined or told off for breaking rules to take their children outside. “The government has never clarified that play is exercise. We know from speaking to families this had a very bad impact and we have seen that the families most fearful of breaking the rules are the most disadvantaged ones.” Alex Foy lives in a flat in south London and said she felt she should be keeping her son, Jamie, at home as much as possible. “The rules made it clear we should stay indoors. I know a walk is acceptable but kids need other kids. Taking him to the park without other children made him even more disheartened and lonely so we avoided it. We did our exercises running up and down the stairs in our flats most days. He was a brave boy but he is a sociable child and he really suffered, he became withdrawn and looked unwell. “He was so excited for school but school isn’t play. He urgently needs to just be himself in a space with other children he cares about.” Daisy Peters, a single mother in Devon, added her views to the letter, saying: “My five-year-old is an only child and she has been badly affected by lack of socialising. Her behaviour has become challenging, she is far less cheerful. Her sleep has also become disturbed.” Shani, a project worker in Bristol, contacted Playing Out because she was so concerned about the impact the rules were having on local families. “Children have been very subdued with us, many have barely been leaving the house because their parents felt it wasn’t allowed. We fear what we are seeing is just the tip of the iceberg.” A government spokesperson said: “We prioritised the physical, mental and emotional wellbeing of young people and made opening schools the first step as we cautiously ease out of lockdown. Schools and after-school clubs are now open. “We fully recognise the importance of exercise to children and know that the risk of transmission is greater indoors than outdoors, which is why playgrounds have also remained open.” Last month ministers were forced to backtrack over guidance that stated only children without gardens could use playgrounds, after an incident where children were told to go home by police while building a snowman.