They have also released images allegedly showing him remotely activating the explosive device.

The arrest of Adham Ahmed Rasheed, 25, came a day after another two suspects, aged 21 and 32 years, were detained, Maldives police said on Sunday.

"We will make more arrests when necessary," Deputy Police Commissioner Mohamed Riyaz said.

The suspect will remain in pre-trial detention for at least 15 days.

Nasheed, 53, the Maldives' first democratically elected president and current head of the parliament, was critically wounded in the IED blast on Thursday.

Rasheed is accused of detonating the explosive device while hiding at the entrance of a guest house five meters away from Nasheed's parked car, according to CCTV camera images released by the police.

The former president's condition is stable after 16 hours of surgery, according to doctors.

The blast also wounded three of his bodyguards and two civilians, including a British citizen.

In 2008, Nasheed became the first democratically elected leader of the island chain some 700 km southwest of India.

Three years after his government was toppled, Nasheed was convicted of terrorism for having fired a judge while president. He was sentenced to 13 years in prison.

He spent a year in custody before being allowed to travel to London for medical care. Once in the United Kingdom, Nasheed successfully applied for political asylum.

When a colleague from his Maldivian Democratic Party won the 2018 presidential election, Nasheed returned to the archipelago and convinced a court to overturn his 2015 conviction, enabling him to be elected to parliament in 2019.

Australian Associated Press