KUALA LUMPUR (Reuters) - A Malaysian artist and prominent opposition activist was jailed for a month on Tuesday for publishing a caricature of Prime Minister Najib Razak looking like a clown, a ruling likely to exacerbate concern about free speech.

Southeast Asia’s third-largest economy recently announced plans to amend a law to stamp out fake news, the latest step to broaden enforcement powers and penalties against online posts or content deemed detrimental to public order and security.

Artist Fahmi Reza was found guilty under a communications law for spreading online content deemed “obscene, indecent, false, menacing or offensive in character with intent to annoy, abuse, threaten or harass another person”.

Fahmi was also fined 30,000 ringgit ($7,700). His lawyer, Syahredzan Johan, said the judge did not give any grounds for the ruling.

“We are appealing the decision,” Syahredzan said, adding that they will post a 10,000 ringgit bond to release Fahmi from custody pending the appeal.

Fahmi faces a second similar charge in a separate court.

Fahmi was among anti-government and opposition leaders and activists rounded up after protests against Najib over his handling of a multi-billion dollar scandal tied to state fund 1Malaysia Development Berhad (1MDB).

The government blocked several websites and news portals carrying reports critical of 1MDB and Najib, despite a longstanding government pledge not to censor the internet.

Najib, who faced a leadership challenge following the 1MDB scandal, is preparing to call general elections that must be held by August. The fund and Najib denied all wrongdoing.

1MDB has been the subject of money-laundering investigations in countries including the United States, Switzerland and Singapore.

In civil lawsuits, the U.S. Justice Department has alleged that about $4.5 billion was misappropriated from 1MDB.