Rio de Janeiro: Leftist leader Luiz Inacio Lula da Silva will be sworn in as Brazil's president on Sunday amid tight security in the country's capital after threats of violence from supporters of his far-right predecessor Jair Bolsonaro.

3 o'clock (1800 GMT) After the ceremony in Congress, Lula will travel to the Planalto Palace to receive the presidential seal in front of 30,000 supporters, and some 300,000 people are expected to gather in Brasilia to celebrate.

After a break during which he spent an additional year and a half in prison due to corruption charges that were later overturned, Lula, 77, defeated Bolsonaro in October to win an unprecedented third presidential term.

Also Read: Indian national perishes in factory fire in Singapore

The former union leader helped millions of Brazilians escape poverty during his tenure as president of the Workers' Party (PT) from 2003 to 2010, while a commodities boom boosted the country's economy.

He now faces the daunting task of reviving Brazil's sluggish economy as well as bringing the country together after Bolsonaro's painful polarization.

Lula is held to a high standard. Creomar de Souza, director of the Dharma Political Risk Consultancy in Brasilia, said the difficult task before them would be to produce results that would enhance the quality of life of the country's citizens.

Also Read: Pope Bendict XVI.. The first pontiff Rest in Peace..

Bolsonaro left Brazil for Florida on Friday to avoid relinquishing the presidency to an opponent whose victory he has not yet acknowledged. By doing so, he also avoided any immediate legal risks associated with his time in office.

Since the election was allegedly rigged two months earlier, Lula's supporters have been calling for a military takeover to prevent him from taking office again amid violence and vandalism.

A supporter detained for making a bomb found on a truck carrying aviation fuel at the airport entrance in Brasilia has admitted he was trying to create chaos to fuel military intervention.

Authorities have sent 10,000 police and soldiers to step up security at Sunday's ceremony and to search attendees - who are not allowed to bring bottles, cans, flag masts or toy guns. Additionally, civilians are currently prohibited from carrying weapons.

Also Read: Guaidó is stripped of his "presidential" duties by the Venezuelan opposition

The King of Spain is among 19 heads of state and government and 50 delegations from 50 different countries who have confirmed their attendance, according to the organisers.

Bolsonaro gave a tearful speech to the nation on Friday before departing for Florida, calling the bomb plot a "terrorist act" but praising the protesters camped in front of army bases.