* Bahrain's government invited the experts
* Office of U.N. rights chief says "deeply concerned"
* Bahrain is staunch U.S. ally, bulwark against Iran
DUBAI, Nov 24 (Reuters) - U.N. Human Rights Commissioner Navi Pillay is sending a team of experts to Bahrain next week to discuss how the Gulf state can improve its rights record amid concerns over Manama's decision to revoke the nationality of 31 people and ban public protests.
Bahrain's government invited the four experts to assess the kingdom's need to improve its track record on the issue, the Office of the United Nations High Commissioner for Human Rights (OHCHR) said in a statement late on Friday.
They will focus on the judicial system as well as on accountability for present and past human rights violations and follow up on a preliminary mission that took place last December, it said.
A staunch U.S. ally, Bahrain has come under increasing Western pressure to implement the recommendations of the Bahrain Independent Commission of Inquiry (BICI) for police, judicial and education reform after last year's government crackdown on pro-democracy protests by majority Shi'ite Muslims.
U.S. officials last week voiced concern that Bahrain's failure to implement key reforms suggested by the BICI report was making political dialogue more difficult and widening divisions in society in a way that might benefit Iran.
"The High Commissioner regretted the decision taken by Bahraini authorities on 7 November to revoke the nationality of 31 citizens for 'having undermined state security'," the OHCHR said.
The decision violated the Universal Declaration of Human Rights which prohibits states from arbitrarily depriving people of their nationality, it said.
The men include London-based dissidents Saeed al-Shehabi and Ali Mushaima, the son of jailed opposition leader Hassan Mushaima, as well as clerics, human rights lawyers and activists, according to Mohammed al-Mascati, head of the Bahrain Youth Centre for Human Rights.
The OHCHR said it was also "deeply concerned about the restrictions on public demonstrations and other public gatherings" declared on Oct. 30.
Bahrain had said the ban was a temporary step to ensure public safety and prevent violence.
The ruling Al Khalifa family used martial law and help from Gulf neighbours to put down an uprising against alleged discrimination in March last year, but unrest has since resumed and Shi'ite protesters and police clash almost daily.
Bahrain, where the U.S. Fifth Fleet is based as a bulwark against Iran, accuses Tehran of encouraging the unrest and has promised a tough response as talks with the opposition have stalled. Iran has denied meddling in Bahrain's affairs.