JAKARTA: Indonesia's main opposition leader Megawati Sukarnoputri called Monday for changes to the country's voter registration procedures only two days ahead of presidential elections.

At a press conference with another presidential hopeful, Golkar party chief Jusuf Kalla, Megawati complained that millions of voters remained unregistered and cast aspersions on the polls' credibility.

"This is to remind all of us that an election is a way to represent the people's sovereignty and to uphold democracy," she said.

The Democratic Party of Struggle leader, who is trailing President Susilo Bambang Yudhoyono in opinion polls, presented her concerns to election officials and was promised the registration problems would be fixed.

She said she expected a ruling from the constitutional court later Monday to allow eligible voters whose names are missing from voter lists to cast their ballots using their identity cards only.

"That will be a breakthrough for a fair election," she said, adding that the election commission had also agreed to work with party officials to fill holes in the voter lists.

The ex-president and daughter of independence hero Sukarno has complained that millions of her supporters have been left off the lists.

She has obliquely suggested that Yudhoyono's supporters are trying to manipulate the vote, claims the president denies.

"We do hope that the other candidate (Yudhoyono) will join us (to complain about the voter lists) but it's difficult to call them," she told reporters.

Wednesday's vote is only the second direct presidential election in Indonesia since the fall of the Suharto dictatorship in 1998.

Liberal ex-general Yudhoyono won the first in 2004, when he ousted Megawati in a landslide.

Megawati made similar complaints about April's general elections but those polls were declared legal and gave a whopping victory to Yudhoyono's Democratic Party, making it the strongest in parliament.

Electoral officials have said they have no intention of delaying Wednesday's vote.

Democratic Party secretary general Ali Marzuki rejected the opposition's concerns, saying voters had had three months since the last election to register.

"Political parties in this case should be more active in encouraging people to register at the nearest electoral office," he told AFP. He said Megawati and Kalla were "just not ready to face a defeat as we all know that all opinion surveys show that SBY's position is unshakeable", he said, using Yudhoyono's nickname.

Some 170 million people scattered across the mainly Muslim archipelago are eligible to vote. A run-off will be held in September if no candidate wins a clear majority.