A Covid-19 disaster is threatening the small southern African kingdom of Lesotho after revelations that the government released people who had tested positive for the virus from quarantine early. Government sources this week said they had been sending Covid-19 patients home from as far back as last June over cost concerns. It comes as the country, the last in Africa to record a case of the virus, recorded a sharp rise in cases in recent weeks after high numbers of workers travelled home from South Africa for the Christmas holidays. According to the latest figures from the National Covid-19 Secretariat (Nacosec), Lesotho had 4,137 cases as of Wednesday, up from 2,137 on 1 December. The country has a population of about 2 million. Moeketsi Majoro, the prime minister, has responded by imposing an 8pm curfew, closing bars and nightclubs, banning sports and closing schools. It came as South African immigration officials estimated that, since Monday, more than 100 travellers a day from Lesotho were testing positive at border points. The department of home affairs said that those who tested positive for the virus were being turned back, except for South African citizens, who were being quarantined. Of about 130,000 people who have entered Lesotho from South Africa since the beginning of December, just 20% had Covid clearance certificates and only about 39,000 were tested for the virus. Thousands more people are believed to have crossed the border illicitly, unable to afford the 800-rand (£38) Covid-19 test, and seven bodies were recovered from the Mohokare River in the last week of December. Police say others are still missing. On Wednesday several minibuses transporting Basotho people without Covid-19 clearance certificates were stopped by the police in South Africa. A Lesotho government source told the Guardian authorities had stopped quarantining travellers because most of those sent to the facilities were not showing symptoms. He said it was decided that seriously ill patients would be sent to hospital. However, the hospitals are also overwhelmed. “We did away with quarantine facilities in June because most of the people sent there were not even showing signs, hence it was a strain on our already thin budget. It was decided that only those who were seriously ill would be sent to hospital. We now owe them [the quarantine centres] over R100m rand (about £4.8m),” the source said. Nacosec risk communications manager Baroane Phenethi said new quarantine facilities were now being identified. “We never anticipated a surge. We are trying to identify quarantine facilities for those who are asymptomatic. Those who are visibly sick would be sent to hospitals,” Phenethi said. He warned of more deaths in the coming weeks. Lesotho authorities have been overwhelmed because of the huge cross-border traffic with South Africa, where cases have also risen exponentially over the festive period. “We are anticipating a rise in cases and even deaths. Cases are rising because people crossed [into Lesotho from South Africa] through illegal borders and are only being tested now when they are returning to South Africa. What’s worse is that the new Covid-19 variant is more severe than the one we had during the first wave,” Phenethi said. Last week the government said it would ensure that at least 200 people a day were tested for Covid-19 in each of the country’s 10 districts. Motlatsi Maqelepo, the health minister, said this would ensure 2,000 results daily. However, a tour of the Maseru testing centre at Makoanyane primary school in Ha Leqele this week revealed that fewer than 100 people were being tested each day. A health worker who wished to remain anonymous said the dire situation was worsening. “The system is overwhelmed and it cannot cope with the huge numbers. Of course, the minister said 2,000 results would be available daily but that is ambitious. “We have a colleague here at Queen Mamohato Memorial hospital who was tested in December and results were expected on the next day. She got confirmation that she had Covid-19 after the hospital authorities begged the laboratory to speed up the process on 2 January. She died two days later. “The situation is bad and we cannot cope.”