A Bulgarian court is to hold a new hearing Thursday in the trial against thirteen religious leaders accused of preaching radical Islam.

The 13 defendants face up to five years in prison in a criminal trial, which is viewed abroad as a test for the limits of religious freedom and tolerance in the country.

The Court in the southern city of Pazardzhik is to hear the expert report of Dr. Hassanov, who is to present a theology analysis of 9 documents translated from Turkish by another expert.

Bulgaria's Chief Mufti, Mustafa Hadzhi and his Deputy Vedat Ahmet have been summoned as witnesses.

At the last session, a translation of religious literature from Arabic to Bulgarian, done by expert Alexander Shurin, was presented before the magistrates. The documents have been found on the defendants' computers.

At the end of 2012, the defense council requested from Shurin to translate all texts instead of only those listed by the prosecution on grounds the latter could be considered intentional selection of evidence. This forced the translator to ask for two extensions of the deadline over the huge volume of literature.

Experts have commented it would be extremely difficult to establish the level of accuracy of the translation. In addition, at the last session, the defense lawyers said the designated experts were not competent enough.

Prosecutors say the Saudi-financed activities of the imams have been spreading religious extremism and that they have used a local soccer team to indoctrinate boys.

Prosecutors allege that three of the imams were undermining the state by encouraging people to boycott parliamentary elections and spreading religious hatred.

The other 10 are implicated in working with Al Waqfal Islami, a Saudi-financed charity that built mosques, sent boys on trips to the Middle East and financed religious education in Bulgaria that prosecutors say embraced the Salafist brand of fundamentalist Islam.

The Bulgarian government closed Al Waqfal Islami in 2003, but prosecutors say the 13 accused continued its work without a license.