Tens of thousands of people chanting anti-government slogans and holding up pictures of jailed activists have taken part in Bahrain's first authorised opposition protest since June.

No clashes occurred at Friday's march along a three kilometre stretch of a highway west of the capital Manama.

Protesters carried Bahraini flags and held up images of rights activist and protest leader Nabeel Rajab, calling for his release.

Bahrain, where the US Fifth Fleet is based, has been in crisis since a revolt led by majority Shia Muslims began 18 months ago to demand democracy in the Sunni-ruled kingdom.

Speaking to Al Jazeera from Bahrain, journalist Reem Khalifa said that since protests started, "It has never been quiet ... especially in the over-populated Shia areas".

"Every day there is tension in various areas around the island,” Khalifa said.

The government has denounced the protest movement, inspired by uprisings elsewhere in the Arab world, as sectarian.

This claim denied by protesters who say they face discrimination from the ruling Sunni minority.

The rally, under the banner "Democratic Freedom" and organised by opposition groups led by the biggest bloc, al-Wefaq, was the first since the interior ministry banned Wefaq-led marches in June, saying these had ended in violence.

Since the ban, protests have continued in villages around the country.

Joe Stork of Human Rights Watch's Middle East division, told Al Jazeera that while he would give the Gulf nation's human rights record "a very bad review", he believes concern over the nation's tarnished image is "having an impact".

"It's also true that some members of the government are very sensitive to their international image. They're concerned about their reputation that Bahrain has gotten over the last couple of years as a place that doesn't tolerate any peaceful dissent," said Stork from Washington.

On Aug 22, protesters pelted police with petrol bombs and stones at the funeral of a teenage demonstrator killed by police gunfire the previous week.

Rajab was sentenced two weeks ago to three years in prison on three counts of leading illegal protests, a verdict that drew criticism from Washington.