A court in Azerbaijan on Monday convicted 15 people accused of ties with Iranian intelligence of crimes including treason and plotting to seize power, and handed down lengthy prison sentences.

The convictions, which a lawyer for the alleged ringleader said were unfounded, highlighted concern in the secular ex-Soviet republic over the influence of neighboring Iran.

The defendants were arrested in January on suspicion of crimes including plotting to forcefully seize power, treason, organizing a criminal group, possession of weapons and drugs, and counterfeiting. Authorities who announced the arrests did not mention Iran. The suspects had been on trial behind closed doors for two months.

The alleged leader, Said Dadashbeyli, and two others were sentenced to 14 years in prison, while the rest received sentences ranging from two years to 13, the Court for Grave Crimes said.

Dadashbeyli's lawyer, Elchin Gambarov, denied the defendants were connected with Iranian intelligence, saying they opposed Iranian influence.

He also denied media reports that portrayed the defendants as Islamic extremists, saying they adhered to "an Islam that is close to democratic values."

"This is an inhuman, unfair court decision," Gambarov said. "Their guilt was not proved." He said the convictions would be appealed.

The oil-rich Caspian Sea nation has increasingly been caught in a tug-of-war for influence between the secular, democratic West and Iran, its large southern neighbor. Rumblings of Shiite political Islam have been particularly noticeable in the more conservative regions that border Iran.

In October, authorities said they had thwarted plans by Islamic militants to attack the U.S. Embassy and other government buildings in Azerbaijan with stolen military grenades and assault rifles.

President Ilham Aliev has maintained a tight grip since succeeding his father in a 2003 presidential vote that observers called flawed. In 2005, authorities arrested 12 government officials on charges of plotting a coup. The opposition said the arrests were part of a government effort to manipulate parliamentary elections that year.