MANAMA, Bahrain: Al-Wefaq National Islamic Society, main opposition group of Bahrain, on Tuesday stormed out of parliament to protest against government manipulation of population data in the Gulf Arab state.

For years the tiny kingdom has officially had a population of about 740,000, but state statistics in February showed it had jumped about 42 percent to 1.05 million.

Bahrain with a majority Shia population is ruled by a Sunni Muslim royal family.

Shias complain of discrimination in jobs and services and accuse the state of giving Sunni foreigners citizenship to dilute Shia influence.

Government officials have repeatedly denied the accusations.

The Shia opposition Al-Wefaq National Islamic Society had accused officials of either negligence or intentionally hiding the true figures after the big population jump appeared suddenly in the statistics. Its members walked out after a probe cleared the state statistics chief of wrongdoing.

"The investigative committee did not hear all the charges of those who called for the investigation ... it was not qualified to conduct the investigation and it was forced upon us," opposition MP Khalil Almarzooq told Reuters.

"We have now objected and withdrawn from the parliamentary meeting," added Almarzooq, speaking for Al-Wefaq which holds 17 of parliament's 40 seats.

The remaining 23 MPs backed an investigative committee's finding that cleared Sheikh Ahmed Attiatullah al-Khalifa, president of the Central Informatics Organisation, of failing to provide accurate population statistics, Almarzooq said.

Sheikh Ahmed was not immediately available to comment, his office said. In earlier comments to newspapers, he has denied any wrongdoing, and said his accusers misunderstood how population statistics were compiled.

Plans for state spending on housing, healthcare and other schemes were now invalid because they used an inaccurate population figure, Almarzooq said. Mainly Shias live in Bahrain's poorer districts.

Pro-Western Bahrain hosts the headquarters of the US Navy's Fifth Fleet.