US Secretary of State John Kerry said democracy was under threat in the Maldives as he added his voice Saturday to criticism over the jailing of the islands' first freely-elected president Mohamed Nasheed.

"We see even now how regrettably there are troubling signs that democracy is under threat in the Maldives where the former president Nasheed has been imprisoned without due process," said Kerry on a visit to neighbouring Sri Lanka. "This is an injustice that needs to be addressed soon."