Myanmar police have arrested two people, who they have labelled "radical Buddhist nationalists," and are seeking several more after they clashed with Muslims in the country's commercial capital Yangon, underscoring the authorities' growing concern over rising religious tensions.

The arrests came after nationalists led by the Patriotic Monks Union (PMU) raided flats on Tuesday in a Yangon district with a large Muslim population, igniting scuffles that were only broken up when police fired shots into the air. Two weeks ago, the same people had forced the closure of two Muslim schools.

"We have arrested two people since yesterday evening, and are still looking for the rest of them," said Police Major Khin Maung Oo, in charge the police station in Yangon's Mingalar Taung Nyunt district, where this week's scuffles took place.

Tensions between majority Buddhists and Myanmar's Muslim minority have simmered since scores were killed and tens of thousands displaced in intercommunal clashes accompanying the onset of the country's democratic transition in 2012 and 2013.

Mutual distrust has deepened since October, when attacks by Rohingya Muslim insurgents in northwestern Rakhine state provoked a massive military counter-offensive, causing around 75,000 Rohingya to flee across the border to Bangladesh.

The 13-month-old administration of Aung San Suu Kyi had made tentative moves against nationalist hardliners, but the arrests mark a significant step-up in the government's efforts, highlighting official concerns over a potential outbreak of violence in the country's main city, which has a substantial Muslim population.‍

Brigadier General Mya Win, commander of Yangon's regional police security command, said extra security forces had been deployed and the police were on high alert to prevent communal violence.

"We are patrolling around Muslim areas and have taken security measures around places of worship," he told Reuters.

Leaders of the nationalist PMU said they were acting independently of the Ma Ba Tha, a larger radical Buddhist and anti-Muslim organization that counts among its leaders the firebrand monk Wirathu, who once called himself "Myanmar's Bin Laden."

Ma Ba Tha holds its nationwide congress in Yangon, a city of more than 5 million that has been a focus of foreign investment since a former military government ceded power in 2012, in two weeks and is expecting about 10,000 monks to attend.

(Source: Reuters)