The economy is crumbling and street protests are turning violent, but Rio de Janeiro put all worries aside for the opening of carnival Friday.

The annual extravaganza marking the last days before Lent in mostly Catholic Brazil was to kick off officially with the handing over of the city keys to the carnival king, a jolly, samba dancing figure known as Rei Momo.

The first samba parades were to get underway at the Sambodromo stadium shortly afterwards, climaxing with the elite contests running through Sunday and Monday nights.

For days, Rio and cities across the country have been gearing up for the party.

Streets are gradually emptying, most businesses are closing until next Thursday, and even the usually raucous chamber of Congress in the capital Brasilia was deserted as the clock ticked down.

The chance to have fun can't come soon enough for Rio, which is reeling from a cocktail of crises that make the glory days of hosting South America's first Olympic Games six months ago feel light years away.

Crime is on the rise and 9,000 troops were deployed on the streets in the run-up to the carnival after relatives of police officers angry at late payment of salaries tried to blockade police stations.

A similar but bigger strike in neighboring Espiritu Santo state paralyzed the entire police force, leading to an orgy of violence, including more than 140 murders in less than a fortnight.

Add in a two-year recession, record unemployment and brutal battles between riot police and anti-austerity protesters in the center of Rio earlier this month, and Cariocas -- as city residents are called -- need a break.

"The carnival looks like a party and it is one, but it's much more than that," said writer Gregorio Duvivier, a prominent carnival participant.

"It often serves to help us put aside our problems for a few days.... I think that it's even greater in time of crisis, because it's even more needed."

- Controversy over mayor -

Carnival is big everywhere in Brazil but nowhere more than Rio, which attracts an estimated one million tourists.

Cariocas have been partying hard in informal street "blocos" for several weeks, but now the serious fun begins with rival samba school parades.

Watched by 70,000 people in the Sambodromo, the parades are intense, heart-pounding affairs where several thousand performers at a time dance and sing in outrageously over-the-top -- and often rather revealing -- costumes.

Their goal will be winning the coveted top prize awarded on Ash Wednesday.

However, the new mayor of Rio, Marcelo Crivella, has indicated he may take the highly unusual step of staying away from the carnival. A powerful member of one of Brazil's richest evangelical churches, which was founded by his uncle, Crivella is believed to disapprove of the sultry carnival scene.

Given the economic and cultural importance of the event in Rio's calendar, his position has puzzled many. As of Friday, it was still not clear whether he would attend the Sambodromo contests, but it was already confirmed that he was sending a deputy in his place to meet Rei Momo.

- Condoms and controversy -

Certainly the city's party faithful are not expected to pay attention to the evangelical movement's dislike for public nudity, drinking and dancing.

The health ministry announced it was distributing some 77 million condoms around the country's carnivals, as well as sending men in condom costumes to join the fun.

The website of Brazil's biggest news organization, Globo, even ran a story Friday titled "Specialists warn about the risks of kissing multiple mouths during carnival."

This year's carnival is also distinctly political, reflecting upheaval in a country still in turmoil after the impeachment of the president last year, ending more than a decade of leftist rule.

One top Rio samba school will recreate an embezzlement scandal under France's King Louis XIV -- a theme with distinctly current overtones in corruption-riddled Brazil.

Another school's parade will depict deforestation and destruction of indigenous lands. The performance has infuriated the country's powerful agribusiness lobby.