The Supreme Court of Cassation (VKS) has launched the trial against Kircho Kirov, the former National Intelligence Service head found guilty of embezzlement by two lower courts.

A final ruling is expected in a month's time, magistrates say.

Kirov's defense demands that the ruling be overturned or that he be acquitted, insisting the trial is politically motivated.

The former spy chief, who worked at the National Intelligence Service (renamed last year to State Intelligence Agency) between 2002 and 2012, became the first high-profile official to be sentenced to jail time in Bulgaria's most recent history.

In May, the Military Court of Appeals in Sofia confirmed the Sofia Military Court's ruling that Kirov is to serve 10 years behind bars, also finding him guilty.

He was indicted in 2013 on charges of misappropriating BGN 4.7 M (approximately EUR 2.35 M) in public funding while in office.

Kirov, who maintains the trial is politically motivated, also says the money was used to recruit informants to what was called National Intelligence Agency at the time (under the new legislation on intelligence passed in the autumn, the body is now called State Intelligence Agency).

The Military Court of Appeals, however, acquitted him of document forgery (in relation to the embezzlement, with prosecutors arguing he created fake documents to justify the expenses)

It also reduced a 15-year ban on holding public offices imposed by the first instance court, shortening it to 13 years.

After leaving the intelligence agency, Kirov took over as security adviser to Prime Minister Boyko Borisov (during his first term of office), but was hastily dismissed.

On Friday he told Focus News Agency that the court's ruling was again political and was linked to the ongoing judicial reform and the forthcoming presidential election.

Kirov is Bulgaria's first ever security chief to be sentenced to imprisonment.