Four political groups in Bahrain have called for a boycott on the eve of parliamentary elections - the first to be held in the Gulf state for nearly 30 years.

Tens of thousands of Bahrainis attended a rally in the capital Manama on Tuesday night organised by the groups.

The boycott call was spearheaded by the Islamic National Accord Association (INAA), the main political group representing Bahrain's majority Shia Muslim population.

"Of course, we will be outside parliament, which will be born handicapped and will be unable to grow and evolve normally," said the INAA leader, Sheikh Ali Salman.

Limited power

The rally was held in the Juffair quarter, home to a sprawling US naval base where the Fifth Fleet is headquartered.

The four boycott groups object to an amendment to the 1973 constitution which would split legislative power equally between an elected chamber and a consultative council appointed by King Hamad bin Isa al-Khalifa.

However, Sheikh Ali praised King Hamad for pushing through democratic reforms.

"Thank you your majesty, without you we would not have been able to meet today in such large numbers," he told the crowd.

"We promise the people and the government to continue to defend in a peaceful and civilised manner the 1973 constitution and to consolidate national unity," Sheikh Ali said.

An elected assembly was dissolved in 1975. Since then the government has been appointing a 40-member Shura consultative council.

Local elections

Bahrain was rocked by political violence in the 1990s as Shia-led protesters demanded change.

Sheikh Hamad wants to modernise Bahrain

King Hamad has introduced reforms since succeeding his father in 1999. The Sunni Muslim Khalifa family has ruled Bahrain for two centuries.

Municipal elections were held in May, in which Islamist candidates polled strongly.

But women - who were given the chance to stand as candidates for the first time - failed to win any seats in the municipal polls.

More than 170 candidates, mostly independents, are contesting Thursday's election. The 243,000 registered voters will elect 37 members of parliament.

The problems of unemployment, corruption, the status of women and government plans to naturalise nearly 10,000 stateless citizens featured prominently in the election campaign.