Wickremesinghe lost the last presidential election in September to Anura Kumara Dissanayake, but has remained politically active despite holding no elected position.He was arrested on Friday as part of Dissanayake's campaign against endemic corruption in the island nation, which is emerging from its worst economic meltdown in 2022.Nalin Bandara, a member of parliament for the main opposition Samagi Jana Balawegaya (SJB) party, who visited Wickremesinghe at Colombo's New Magazine Prison, said the former leader had called for unity to challenge Dissanayake's leftist government."What the former president says is that we should get onto a common stage to fight the oppression of the new government," Bandara told reporters outside the prison.Wickremesinghe's own United National Party (UNP), which has two seats in the 225-member parliament, said the government felt threatened by the former president."They fear he might return to power, and that is why this action," UNP General Secretary Thalatha Athukorala told reporters in Colombo.Wickremesinghe stands accused of using state funds to finance a private visit to Britain in September 2023, while returning from attending the G77 summit in Havana and the UN General Assembly in New York.The offences carry a maximum punishment of 20 years in jail and a fine not exceeding three times the value of the misappropriated funds estimated at 16.6 million rupees (US$55,000).His two-day UK visit was to participate in the conferring of an honorary professorship on his wife, Maithree, by the University of Wolverhampton.Wickremesinghe has maintained that his wife's travel expenses were met by her and that no state funds were used.Wickremesinghe became president in July 2022 after then-leader Gotabaya Rajapaksa stepped down following months of street protests fuelled by the economic crisis.