Thousands of Iraqis took to the streets of Baghdad and cities in the Shiite-majority south of the country on Friday to condemn Bahrain for crushing an uprising a year ago.

The protests, organised by Shiite cleric Moqtada al-Sadr, took place in a half-dozen cities in south Iraq with attendance ranging from dozens to several thousand, AFP reporters said.

"The Bahraini king is a king only to himself, not for the oppressed people of Bahrain," Sadrist official Ibrahim al-Jabari said in a speech to thousands of demonstrators in the movement's Sadr City bastion in north Baghdad.

Jabari also criticised the Arab League for barring Syria from attending an upcoming summit in Baghdad, but allowing Bahrain to join.

Protesters shouted, "Bahrain! Free, Free Bahrain!" and held banners condemning Saudi Arabia's "interference" in the Gulf monarchy.

Rallies were also held in Sadr's headquarters town of Najaf, the southern port city of Basra, and the towns of Nasiriyah, Hilla, Amara and Diwaniyah.

AFP journalists said thousands of demonstrators attended the Najaf and Amara protests, while hundreds took part in the Basra, Nasiriyah and Hilla rallies. Diwaniyah, however, only say a few dozen protesters.

"All of these protesters have come to say to the Bahraini leaders, 'Stop what you are doing to the people of Bahrain'," said Mohaned al-Gharawi, a Sadrist official taking part in the Najaf demonstration.

Bahrain has complained to Iraq previously of Sadr's "irresponsible statements" about the uprising, summoning Baghdad's envoy to Manama in January.

The Shiite-led opposition in Bahrain demands constitutional changes that would reduce the power of the ruling Sunni dynasty. Tensions have remained high in Bahrain since a deadly crackdown last year after a month of street protests in the capital Manama.

Tensions between Iraq and the six Gulf Arab states have risen sharply since Bahrain secured military support from fellow Gulf Cooperation Council members to smash the month of pro-democracy protests.

In the aftermath of the crackdown, Iraqi Prime Minister Nuri al-Maliki warned that the military intervention risked stoking sectarian conflict across the region.