Malaysian opposition leader Anwar Ibrahim has been charged with defying a controversial court order banning street protests, in a case he says is politically motivated.

Anwar and two members of his opposition party were charged Tuesday with violating the Peaceful Assembly Act last month by taking part in a massive street protest to demand electoral reforms.

Tens of thousands of protesters took part in the April 28 rally after breaching a police barricade aimed at keeping them out of Kuala Lumpur's central Independence Square.

Police used tear gas and water cannons during the protest, which was Malaysia's largest in a decade.

The 64-year-old Anwar on Tuesday said the charges against him are the latest attempt by Prime Minister Najib Razak to intimidate his political opponents ahead of elections that could be held later this year. The prime minister denies the charges.

Rights groups have called on the government to withdraw the charges against Anwar and rewrite the Peaceful Assembly Act. The law was enacted last year, replacing a previous law requiring all protests to be approved by local police officials.

But Mickey Spiegel, a senior Asia researcher for Human Rights Watch, told VOA that the new law has not improved freedom of assembly for Malaysians.

“It's much worse. We see people who were actually charged with “protests.” And protests were initially called something like “moving assemblies,” which meant that anyone who was moving, any demonstration that involved a march, was in fact illegal.”

Spiegel says the government also banned all protests within a certain distance of a large number of public locations, making it – in her words – “almost impossible to have a rally any place in urban Malaysia.”

Activists claim that the Election Commission is biased and that Prime Minister Najib's ruling coalition, which has held power for 55 years, will have an unfair advantage in elections that could be called as early as June.

Most observers expect a tight contest after the Anwar-led opposition handed Prime Minister Najib's coalition its worst electoral result ever in 2008.

The charges against Anwar come just months after the former deputy prime minister was acquitted on charges of sodomizing a former male aide. He was first forced to resign in 1998 after his conviction on an earlier sodomy charge. The Supreme Court threw out that verdict in 2004.

If convicted of the latest charges, Anwar could face a large fine, a jail sentence, or disqualification from political involvement.