Police in the northern Moroccan city of al-Hoceima have fired tear gas to disperse hundreds of protesters and stop them marching in defiance of a government ban.

Organisers from the al-Hirak al-Shaabi movement dubbed the demonstration the "million-man march" and said it was aimed at protesting "against repression".

Scores of police could be seen around al-Hoceima since early morning on Thursday, and by early afternoon they began sealing off access to all main squares, AFP news agency reported.

By late afternoon hundreds of people began gathering in several meeting points across the city intent on marching as planned, but as they tried to advance the police charged and pushed them back.

Al-Hoceima, the main port in the Rif region, has been hit by unrest since a fish seller was crushed to death in a rubbish truck last year as he tried to retrieve swordfish confiscated for being caught out of season.

Calls for justice snowballed into a wider social movement demanding jobs, development, and an end to corruption in the mainly Berber region, where residents have long complained of neglect and marginalisation.

Hirak has won strong support among the region's diaspora, and many former Rif residents living abroad had returned to the city to join the march.

Ali, a political science researcher from al-Hoceima living in Canada, said he had returned to the city to "show my support for the Hirak movement".

Continued tensions

Hours before the protest was to kick off, activists said on Facebook that police had blocked protesters from entering the city, citing "high orders".

Most shops in the city were closed, and there were reports that the Internet and phone service had been temporarily turned off.

In the Sidi Abed neighbourhood, police fired tear gas at demonstrators who were chanting "Long live the Rif" and "Long Live Zefzafi" - in reference to jailed Hirak leader Nasser Zefzafi.

Witnesses said demonstrators hurled stones at the police as they charged and knocked some to the ground, and that the security forces threw stones back at them.

"We are in a country where there is no freedom of expression. We have asked for hospitals, jobs, public transport. What is wrong with that?" asked one of the protesters on Thursday.

Police arrested around 12 activists, including the head of a news website, Hamid El Mahdaoui, according to local journalists.

READ MORE: Morocco - What is fuelling unrest in the Rif?

Among Hirak's demands are calls for a serious inquiry into the death of Mohcine Fikri, the fish seller; release of political prisoners; and the construction of universities, hospitals and libraries in Rif.

The movement gained traction in recent months after the arrest of Zefzafi, along with 150 of his fellow activists, led to solidarity marches and clashes across the country.

A solidarity march in the capital city Rabat last month drew more than 100,000 protesters, the most since the 2011 regional uprisings.

Tensions have eased in recent weeks and earlier this month security forces reduced their presence in al-Hoceima and another northern city Imzouren, which had been on virtual lockdown.

Authorities have promised to do more to help the region and relaunched a 2015 programme to improve its infrastructure, health facilities and education services by 2019.