MEXICO CITY (Reuters) - Honduran President Juan Orlando Hernandez on Wednesday said he would seek re-election next year, despite warnings from the opposition that his plans violate the constitution of the violent Central American nation.

The Supreme Court paved Hernandez' way by issuing a ruling last year that overturned an explicit constitutional ban on presidential reelection, after the 2009 ouster of former leftist President Manuel Zelaya who sought a referendum on the issue.

The president, who gained popularity by cutting the murder rate through his aggressive fight against drug trafficking and gangs, said he would only seek one more term, from 2018-2021.

Hernandez, a conservative lawyer who took office in 2014, is the favorite to win his National Party primaries in March.

Opposition politicians slammed the decision, saying the judicial ruling was unconstitutional and violates the Democratic principle of alternating leaders in power.

"This is the same situation as in 2009. Reelection is illegal in Honduras and puts us on the path to a crisis," said Romeo Vásquez, the retired general who led the coup against Zelaya and who now heads a small opposition party.

(Reporting by Gustavo Palencia and Enrique Pretel; Editing by Sandra Maler)