A Republic of Congo tribunal has sentenced an opposition leader to two years in prison for inciting public disorder and insurrection.

The lawyer for United Party for Congo head Paulin Makaya said Monday the sentence, including a $4,000 fine, is unjust. Yvon Eric Ibouanga said an appeal will be filed.

Makaya was detained after participating in an October protest. Opposition leaders called for a boycott of an Oct. 25 referendum that ultimately passed, allowing the country's longtime president to seek another term.

Amnesty International says the sentence shows that freedom of expression is restricted in Republic of Congo. The organization has called for Makaya's immediate and unconditional release, calling him a prisoner of conscience.

President Denis Sassou N'Guesso, in power for more than 30 years, was re-elected in March.