YANGON (Reuters) - Myanmar’s top Buddhist authority banned a hardline monks’ group on Tuesday, raising pressure on extremists after they barred a firebrand monk from public sermons and authorities arrested several Buddhist nationalists.

The radical group known by its Burmese initials Ma Ba Tha was declared illegal and “no person or organisation” is allowed to use its name, according to a statement issued by the Sangha Maha Nayaka Committee, the country’s highest Buddhist authority.

All signs with the group’s name must be removed by July 15, the statement said, and anyone who does not comply with this ban will be charged under the law.

Tensions between majority Buddhists and Myanmar’s Muslim minority have simmered in Myanmar since scores were killed and tens of thousands displaced in intercommunal clashes at 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.

Ma Ba Tha, or the Committee for the Protection of Nationality and Religion, had wielded significant political clout in recent years, successfully campaigning for the passing of laws seen by rights groups as discriminating against Muslims.

One of its leaders is Wirathu, a radical monk who once called himself “Myanmar’s Bin Laden” and denounced the United Nations’ human rights investigator Yanghee Lee as a “whore”. He was recently barred from preaching.

Religious tensions in Myanmar have been high. Police last week arrested several hardliners following their clashes with Muslims in the country’s largest city, Yangon.

Ma Ba Tha’s chairman Tilawka Bhivamsa confirmed he had signed the statement but refused to comment further.

The group had planned a nationwide conference in Yangon this weekend, expecting about 10,000 monks to attend.

In the runup to the 2015 election that ushered in the government of Aung San Suu Kyi, Ma Ba Tha organised a massive rally attended by thousands in Yangon.

Suu Kyi’s National League for Democracy party did not field Muslim candidates in that election out of fear of coming under attack by radical Buddhists.

Tun Nyunt, a director at the Religious Affairs Ministry told Reuters the government received the statement and was distributing it to local chapters of the Sangha and regional officials from his ministry.