SAO PAULO, May 12 (Reuters) - Light SA has filed for bankruptcy protection with some 11 billion reais ($2.2 billion) of debt, it said on Friday, making the utility the latest high-profile Brazilian firm to seek such protection in recent months.

Light, which distributes power in Rio de Janeiro state, joined the ranks of retail giant Americanas SA, telecoms firm Oi SA and brewer Petropolis, which have all filed for bankruptcy this year amid financial crises.

Light said in a securities filing the request before a court in Rio de Janeiro came as the economic and financial conditions of the firm and some of its subsidiaries continued to worsen despite efforts to meet financial obligations.

That required "the urgent adoption of other measures that can protect them until it is possible to implement the readjustment of its indebtedness and the readjustment of its capital structure," Light said.

Shares of the company, which has Ronaldo Cezar Coelho's investment fund Samambaia FIA as its largest shareholder, fell more than 17% to 3.85 reais in morning trading after the news.

The electric utility had earlier this year already requested a court to temporarily suspend payments of financial debts.

It said it was "confident" in its operational capacity as well as in its commercial reach to approve the reorganization plan also aimed at preserving its services, a view shared by the state of Rio de Janeiro.

"We understand the financial issues must be resolved within the process, in talks with creditors, while the services provided by the company would remain normal," Rio's Chief of Staff Nicola Miccione told Reuters.

Earlier this week, Brazil's Mines and Energy Minister Alexandre Silveira criticized Light, saying that companies with "no management efficiency ... such as Light," should not get their distribution contracts renewed.

Light at the time declined to comment.

($1 = 5.0033 reais) (Reporting by Gabriel Araujo; Additional reporting by Leticia Fucuchima and Rodrigo Viga Gaier; Editing by Steven Grattan and Mark Potter)