Kyrgyzstan on Friday said it has prevented two major attacks by militants linked to the Islamic State group, one of which would have targeted a Russian airbase in the ex-Soviet Central Asian country.

The security service said its forces on Thursday conducted a raid in the centre of the capital Bishkek, killing four suspected "terrorists" in an hour-long shootout.

Security forces shot dead two more people in a separate raid in a suburb of the city, said Rakhat Sulaimanov, the spokesman for Kyrgyzstan's committee for national security (GNKB).

"The terrorists who were liquidated were connected to the Islamic State (IS)," Sulaimanov said. The jihadist group is banned by the government in Kyrgyzstan, a Muslim-majority country.

"The members of the international terrorist organisation were planning to stage a blast at the Kant airbase in order to take control of the weapons and ammunition of the strategic Russian facility" and arm militants, he said.

Russia's Kant base is located about 20 kilometres (12 miles) west of Bishkek.

The same IS cell was planning to "organise terrorist acts in populated areas" of Bishkek on Friday, when Kyrgyzstan celebrates the Muslim holiday of Eid that marks the end of the Ramadan fast, the security service said.

A statement by the GNKB published Friday said that the cell was headed by a Kazakh national, Zhanbolat Amirov, who had escaped prison.

Seven suspected members were arrested during raids on Thursday, during which four security officers were injured, it said.