Kenya's President Uhuru Kenyatta arrives to inspect a guard of honor before the annual State of the Nation address at the Parliament Buildings in Nairobi. Picture: Reuters/Thomas Mukoya

Nairobi - Kenya's President Uhuru Kenyatta signed a new law on Wednesday that outlaws the abuse of people on social media but which critics say could be exploited to repress civil liberties.

Proponents of the law, including the legislators who pushed it through parliament, say the proliferation of social media has given rise to new crimes including online scams, which were not covered by previous laws.

New York-based media rights watchdog the Committee to Protect Journalists (CPJ) warned last week however that the bill could criminalise free speech, "with journalists and bloggers likely to be among the first victims if it is signed into law".

The law lays the ground for investigation and prosecution of computer and cybercrimes including cyber-harassment and "publication of false information", a statement from the presidency said.

Read more: Kenyatta urged not to sign cybercrime bill into law

Violations to be penalised under the law include cyber-espionage, false publications, child pornography, computer-borne forgery, cyber-stalking and cyber-bullying among others, the statement said, without spelling out the penalties.

Offenders convicted for sharing "false" or "fictitious" information and propagating hate speech will be liable to a fine of 5 million shillings (about R600 000) or sentenced to two years in jail, or both.

Lawmakers passed the bill last month despite protests from media practitioners and rights activists that its provisions could be used to stifle press freedoms.

Kenya joins other countries in the region that have passed laws that activists say will curtail free expression.

Earlier this month, Tanzanian bloggers and rights activists won a temporary court injunction against a government order to register online platforms that raised concerns about a crackdown on free speech.

In April, Uganda, another East African country acting to regulate internet use, announced plans to slap a new tax on social media users.