BAKU, Azerbaijan — A court in Azerbaijan on Friday jailed the head of an independent news agency pending an investigation on tax evasion charges, a move that the opposition denounced as an attack on freedom of speech in the ex-Soviet nation.

The court in Azerbaijan’s capital of Baku put Turan news agency director Mehman Aliyev in prison for three months. He was arrested Thursday night.

Tax authorities have accused Aliyev of failing to pay the equivalent of nearly $22,000 in taxes in 2014-2016.

His lawyer, Fuad Agayev, called the charges political, saying that Turan has fully paid all taxes.

“The charges are absolutely unfounded and have no legal grounds,” he said.

Turan has denied the charges. It said its bank accounts have been blocked by authorities, forcing it to halt operations starting Sept. 1.

International rights groups have repeatedly criticized the oil-rich Caspian nation for cracking down on independent media and opposition activists.

The opposition Musavat party and National Council movement criticized Aliyev’s arrest as the latest attack on media freedom and called for his release.

“The tax agency has been used as a weapon against independent media,” the National Council said.

Azerbaijan’s journalists association has appealed to the country’s president to intervene in the case.