Malaysia's opposition camp began a legal battle Monday challenging results of last month's general election, alleging the ruling coalition won 24 parliamentary seats through irregularities.
The three-party opposition alliance won 89 seats in the 222-seat national parliament, just 23 seats short of a majority.
Rafizi Ramli, a strategist for the opposition People's Justice Party, said the party began filing court petitions Monday and will continue to file court papers until the petition deadline closes Wednesday.
The 13-party National Front coalition under Prime Minister Najib Abdul Razak has hung on to power after the Elections Commission declared it winner of the May 5 general election.
The opposition refused to concede defeat, accusing the National Front of vote-rigging and gerrymandering in complicity with the Elections Commission.
The National Front has ruled the country since Independence.
Separately, the opposition is taking legal action against Home Minister Zahid Hamidi for allegedly violating the election law that limits election spending to 200,000 ringgit (about $64,000).
The opposition is also taking legal action against the entire Elections Commission board for allegedly failing to oversee the use of indelible ink in balloting.
There were reports the supposedly indelible ink could be washed off easily.
Last month's poll was the first time the ink was used to prevent double voting.
Another petition is also being mulled seeking the courts to review the electoral roll, which Rafizi said is tainted with "phantom voters," especially in Sabah State.
"The crux of the issue is that we have a defective, biased and unfair Elections Commission," Rafizi told Kyodo News.
The commission has insisted that last month's general election was held according to the law and denied allegations of bias.
The opposition, however, is likely to face an uphill legal battle.
A total of 29 election petitions were filed after the 2008 general election, but only one was successful.
After the election, the opposition took their case to the streets with nationwide rallies, which attracted tens of thousands of participants.
A major rally is planned for June 22 in Kuala Lumpur, but organizers are wrangling with the authorities over the venue for the protest.
Faced with public pressure, Najib last week announced plans for a bipartisan parliamentary panel to oversee the Elections Commission, saying he hopes the move will "strengthen public confidence" in the election watchdog.