Bayaman Erkinbayev was shot dead in September

Tashtemir Aitbayev, head of Kyrgyzstan's security service, said on Tuesday that Erkinbayev met a prominent mafia leader shortly before he died.

Mr Aitbayev said that the dead MP had refused to deliver 20kg of heroin to a prison.

Erkinbayev, 38, was one of three MPs murdered since March.

He was shot on 21 September in the neck and chest as he arrived by car at his home in the capital, Bishkek.

There had been speculation that his killing could have been politically motivated, as he was considered a prominent force behind protests earlier this year which saw the ousting of former President Askar Akayev.

Erkinbayev was a wealthy businessman in southern Kyrgyzstan, where the anti-Akayev protests began.

Since the change in Kyrgyzstan's administration in March the country has seen considerable instability.

MP Jyrgalbek Surabaldiyev was shot dead in Bishkek in June, and another politician, Tynchbek Akmatbayev, was shot dead during a prison visit in October which culminated in widespread unrest throughout several of the country's penitentiaries.