There was a heavy police presence around a central square in the capital of ex-Soviet Azerbaijan on Saturday ahead of an unauthorised pro-democracy protest which the authorities have vowed to stop.

An AFP reporter saw groups of police with batons, shields and riot helmets in streets leading to Fountains Square in the capital of the energy-rich, mainly Muslim state.

The leaders of two main opposition parties, the Azerbaijani Popular Front and Musavat, were summoned to Baku's main police station on Friday and warned that the rally would be illegal.

Rights groups said that more than 10 opposition supporters were arrested the day before the planned protest.

"The Azerbaijani government's pre-emptive crackdown on those seeking reform has been wide-reaching and ruthless," said John Dalhuisen of Amnesty International on Friday.

On 11 March 2011, police thwarted attempt by the opposition in the tightly-controlled state to latch on to the Arab revolts.

Activists had called for the March 11 "Great People's Day in Azerbaijan" protest against the authorities led by President Ilham Aliyev -- who succeeded his father Heydar in 2003 -- through the Facebook website.

Opposition parties complain of a lack of democratic rights and free speech in Azerbaijan, which is an important supplier of oil and gas to the West. Critics have accused the West of tempering criticism of rights abuses in order to safeguard their economic interests in the Caspian Sea state.