BANGKOK (AP) — Student activists at Thailand’s most prestigious university defied a ban by college administrators and staged an anti-government rally on Friday, as a prominent protest leader was arrested elsewhere for his involvement in a previous demonstration.

Hundreds of students gathered in a hall on the campus of Chulalongkorn University in central Bangkok to hear speeches calling for a new constitution and for the government to resign. A heavy rain forced a change of venue from an outdoor plaza and may have discouraged attendance.

The rally was banned by the university, which said it allows nonviolent political gatherings but was given too short notice to ensure safety. Protest organizers announced they would go ahead with the event anyway, even though those taking part were threatened with possible punishment.

The rally was the latest in a series in several major cities around the country.

Several activists involved in organizing earlier protests have been arrested on various charges, including sedition. Police on Friday stopped a car carrying Parit “Penguin” Chiwarak and arrested him on a sedition charge in connection with a July 18 protest.

His arrest in a northern suburb of Bangkok, as he was reportedly traveling to a protest at another university, was shown in a video on his Facebook page.

The protests have been gaining steam for several weeks but took a controversial turn on Monday, when some speakers at another university north of Bangkok openly criticized aspects of Thailand’s constitutional monarchy.

The openness of that challenge to what is traditionally the country’s most revered institution sent shock waves through the country. The monarchy is protected by a draconian defamation law that carries a penalty of up to 15 years in prison.

It also put pressure on the government to crack down harder on the protest movement, at the risk of stoking further discontent among supporters of the student activists.

The wave of protests has pressured Prime Minister Prayuth Chan-ocha’s government, whose competence to run the economy was already in question before the pandemic, with growth struggling in comparison with Thailand's Asian neighbors.

The growing anti-government agitation has mainly taken aim at its perceived illegitimacy. Prayuth, a former army commander, originally seized power in a coup in 2014. He retained it last year in an election under rules that opponents say were drawn up to all but guarantee his victory.