Bahrain's opposition said on Wednesday that an agreement on the mechanism of a planned national dialogue should be agreed before the start of the talks aimed at ending the kingdom's political deadlock.
The Shiite-led opposition's position could mean that the dialogue might not start on Sunday if it sticks to its demands and shuns the talks, as it has in the past.
The opposition groups "stressed the need to agree on the mechanism and the rules of the national dialogue," said the six opposition groups, led by Al-Wefaq, in a statement ahead of the dialogue.
"Agreeing on the mechanism before the dialogue starts would strengthen public trust in the dialogue," they said.
It would also "spare" Bahrain from the failure of the talks in the first round, a situation that would have unwanted "political and public implications," they added.
The opposition groups have decided to again write to the justice minister on Thursday to stress their position, and to renew their request to meet him to agree over the mechanism of the dialogue, the statement said.
The minister, Sheikh Khalid bin Ali al-Khalifa, announced on Monday that the dialogue would resume on February 10, after an earlier round failed to the bring the opposition on board.
He said the dialogue would reconvene on Sunday after he met representatives of six opposition groups and other political associations.
But the opposition groups said on the same day they wanted clarifications on the mechanisms, and asked for an agenda and time frame, in addition to the nature of government involvement, insisting on its strong representation "to avoid procrastination".
King Hamad called in January for a new round of talks in a move cautiously welcomed by the opposition which had shunned earlier invitations, as protests rumble on despite a heavy-handed crackdown on demonstrations in March 2011.
The opposition has repeatedly said it is ready for a meaningful dialogue, but has stuck to its demands for a real constitutional monarchy with an elected prime minister.
Al-Wefaq, which had pulled out of a similar round of talks in July 2011, said in December it was ready for new dialogue.
Bahrain has been shaken by unrest since its forces crushed popular Shiite-led protests two years ago demanding greater rights and an end to what the opposition said was discrimination by the Sunni royals.