Authorities in Bahrain on Saturday expelled two American human rights activists, accusing them of violating tourist visa rules by joining anti-government demonstrations in the Persian Gulf kingdom.

The authorities said the women, identified as Huwaida Arraf and Radhika Sainath, were ordered out of the country after being arrested during a protest in the capital Manama, ahead of the one-year anniversary of the Shi'ite-led uprising against the country's rulers.

Tensions have run high in Bahrain as the opposition and activists prepare to commemorate the protests aimed at breaking the Sunni minority's hold on power in the Shi'ite majority nation.

Authorities responded with widespread crackdowns and arrests. At least 40 people have died in the unrest.