MANAMA, Bahrain—Bahrain's largest Shiite opposition group, al Wefaq, said Friday it will participate in talks with the government, after the king said he would set up an independent inquiry into the violent crackdown on protesters earlier in the year.

But al Wefaq warned it will withdraw from the so-called national dialogue if its core demands, including a fully elected Parliament with complete legislative powers, aren't met. The government-sponsored talks are due to start Saturday and last a month.

"This is not credible dialogue, but we will strive to get our demands," said Khalil Almarzooq, a senior al Wefaq member. He said the group's decision to accept the dialogue was partly motivated by fear of international criticism if they snubbed the talks.

Al Wefaq has called the national dialogue a sham, saying it under-represented Bahrain's formal political opposition, and some had expected the group to decline to take part. The group said that out of the 300 people the government invited for talks, only about 50 are from the formal political opposition. The rest, it said, is made up of pro-government civil and political societies and business leaders.

Analysts said the group's 11th-hour decision to participate was due to fears of being sidelined further in the political process. All 18 Wefaq members of Parliament resigned in February in protest of the government's initial crackdown on protesters.