(AFP) - Mauritius votes Sunday in an election overshadowed by a wire-tapping scandal that has rocked the Indian Ocean archipelago amid fears that rights are eroding in one of Africa's biggest success stories.

The legislative poll comes as the country celebrates the historic deal last month that saw Britain relinquish sovereignty of the remote Chagos Islands to Mauritius following a long-running legal dispute.

But Prime Minister Pravind Jugnauth's hopes of an easy re-election were battered when secretly recorded phone calls of politicians, diplomats and journalists began to be leaked online in October.

The authorities responded last week by banning social media until after the election. But an uproar from the opposition and local media forced an embarrassing climbdown within 24 hours.

Mauritius, a country of 1.3 million people, has seen remarkable stability and growth since independence from Britain in 1968, building an economy based on tourism, manufacturing and financial services.

More than one million people are registered to vote in the 12th legislative election in Mauritius since independence, but there are fears that its lauded democracy is eroding.

"In the last five years, the institutions that were ensuring checks and balances have not been functioning and corruption has increased," said democracy researcher Roukaya Kasenally.

She highlighted procurement scandals during the Covid-19 pandemic, harassment of opposition parties in parliament, and the use of police against political opponents.

Mauritius last month slipped from the top spot to second place in the latest Ibrahim Index, which monitors governance across the African continent.

The index highlighted worsening discrimination, which Kasenally put down to the "systematic" disadvantages faced by the Creole population descended from African slaves.

The Creole population has struggled for representation in Mauritius, which is predominantly Hindu but has sizeable Christian and Muslim minorities.

"After independence we developed this democratic success story and 'Mauritian miracle' economy, and never thought we were going to backslide," said Kasenally.

"But because of that, a number of issues were not seriously addressed," she added, including the winner-takes-all election model that means single coalitions often dominate parliament.

- Rotating families -

Just three families have rotated the leadership of the East African island group since independence.

Jugnauth, 62, inherited the premiership from his father when he died in 2017, before winning by a wide margin at the 2019 election as head of the Militant Socialist Movement (MSM).

He is hoping to build on the MSM-led  alliance's majority of 38 seats in the 70-seat National Assembly and win a new five-year term.

His main opponent is Labour Party leader Navin Ramgoolam, 77, of the progressive Alliance of Change -- himself a former premier and son of the country's first leader.

However, the established leaders face a new outside challenge from the Linion Reform alliance, campaigning under the slogan "Neither Navin, Nor Pravind".

It has criticised corruption, nepotism and called for greater transparency -- which may hit home in the aftermath of the wire-tapping leaks.

The deal with Britain over the Chagos archipelago was a major success for the government, however, even if the UK will retain a lease to keep a joint US military base on the island of Diego Garcia for an "initial" 99 years.

Commentators in Mauritius have suggested that president-elect Donald Trump's approach to the US presence in the Indian Ocean could impact the Chagos agreement.

© Agence France-Presse