A top Azerbaijani investigative journalist and anti-graft campaigner, who accused the country's president of corruption, went on trial Friday on charges she denounced as politically motivated.

Considered the energy-rich country's most prominent journalist, Khadija Ismayilova faces up to 12 years in prison if convicted on a string of charges including embezzlement and tax evasion.

She has been in pre-trial detention since December.

"I am being persecuted for exposing corruption in Aliyev's family," she told the court in the capital Baku, referring to President Ilham Aliyev.

She told the judge that the charges against her were "falsified and politically motivated."

Ismayilova, 39, received a thunderous ovation from supporters outside the court building as she was escorted to the courtroom earlier Friday.

Dozens of police cordoned off the street outside the Court for Serious Crimes, forbidding a number of journalists and foreign diplomats to attend the trial.

The judge rejected her lawyer's application for the case to be thrown out or for Ismayilova to be released on bail.

"All charges against my client are groundless," her lawyer Fariz Namazly told AFP. "It's a trumped-up case."

Ismayilova, who served as bureau chief for the local service of the US-funded Radio Free Europe/Radio Liberty network between 2008 and 2010, is charged with inciting a former colleague to commit suicide, tax evasion and embezzlement.

She was put in the dock after leading rights activist Leyla Yunus and her husband went on trial last week on charges of committing economic crimes that the couple say are politically motivated.

The high-profile trials kicked off after Azerbaijan last month hosted with great fanfare the inaugural edition of the European Games, a sporting extravaganza billed as Europe's answer to the Olympics.

The same month rock singer and political activist Bono spoke out in support of six jailed activists including Ismayilova and Yunus.

This week Freedom House, a US-based watchdog, urged the United States and other governments to "condemn these trials for what they are – farcical, politically motivated attempts to silence dissent in Azerbaijan and hide government corruption."

- 'Defamed under pressure' -

A former journalist at Radio Liberty's Azerbaijani service, Tural Mustafayev, had claimed earlier that he attempted suicide last October because Ismayilova sacked him several years earlier.

But during Friday's hearing Mustafayev testified that he had "defamed" Ismayilova under pressure from law enforcement agencies.

"I expect a harsh verdict," Ismayilova told AFP from prison in June.

"They will steal some 10 years of my life, but I am not scared."

Her arrest in December sparked international condemnation, with rights watchdog Amnesty International calling her a "prisoner of conscience."

The Committee to Protect Journalists, a nonprofit organisation that promotes press freedom, called on Azerbaijani authorities to immediately release Ismayilova.

"Azerbaijan should do the right thing and free Khadija Ismayilova, along with all other journalists imprisoned in the country," the New-York-based group said on Thursday.

"This would be a crucial first step in addressing Azerbaijan's tarnished image which reached a new low amid the European Games last month."

- 'Enemy of the government' -

Ismayilova, who has won several awards for exposing corrupt officials in the Caspian Sea country, has said she is being harassed because of her work.

"The truth is that Azerbaijan is in the midst of a human rights crisis," she said in an open letter published by the New York Times in June.

"Things have never been worse," she wrote, adding that she was pressing ahead with her investigative work from jail.

In a leaked diplomatic cable from 2009 published by Wikileaks, Aliyev is said to have described Ismayilova as an "enemy of the government", asking the US ambassador to Azerbaijan to intervene to have her sacked by Radio Liberty.

In December, Azerbaijani police raided and closed the Baku offices of Radio Liberty in a move that has left Washington "deeply disturbed", aggravating concerns about the treatment of non-state media in the Caucasus nation.

Freedom House says there are now more than 80 political prisoners in Azerbaijan.