RIO DE JANEIRO, Jan. 24 (Xinhua) -- A Brazilian appeals court on Wednesday upheld the corruption conviction of ex-President Luiz Inacio Lula da Silva.

The decision is likely to sideline Lula's plans to compete in October presidential elections, though he can still appeal to a higher court.

The three-judge panel voted unanimously to ratify his conviction and to extend his original sentence from nine and a half years in prison to 12 years.

In an initial trial, Lula was found guilty of receiving bribes from construction company OAS in the form of a beachfront luxury apartment in Guaruja, Sao Paulo state. He denies owning the property and said he considered buying the apartment but ultimately decided against the purchase.

Lula's trial is considered the single most important political event of the start of the year, because of its potential to change the scenario of the presidential elections.

The decision could leave Brazil's Workers' Party (PT) without a viable candidate.

Lula, arguably Brazil's most popular politician, consistently leads polls comparing the potential presidential candidates. He has said the accusations against him were politically motivated.