A massive army of Islamic State (ISIS) fighters coming from various nations are massing on Afghanistan's northern border ready to march and conquer neighbouring states, Russian intelligence officials have revealed.

At the same time, Russian President Vladimir Putin is reportedly planning a huge ground operation in Syria involving 150,000 Russian soldiers to seize the ISIS stronghold of Raqqa and once and for all wipe out the jihadist group. Raqqa is the self-declared capital of ISIS in Syria and is reportedly guarded by as many as 5,000 Islamist fighters, the Daily Express reported.

Russian spy chief Alexander Bortnikov reportedly warned Moscow that heavily armed fighters from the Taliban could join ISIS in its planned invasion of Central Asia.

Speaking at a meeting of special services from the Commonwealth of Independent States, he warned: "The international community has now hit a new geopolitical challenge, an international criminal group in the name of the Islamic State.

"This project, which grew out of the 'Arab Spring,' has gained momentum thanks to the double standards of certain world regional powers by using 'a terrorist battering ram' to reach their own strategic goals in Asia and Africa.

"According to our estimates, citizens from more than 100 countries are currently fighting in the ranks of terrorist structures and the recruits constitute up to 40 percent of their forces.

"The escalation in tensions in Afghanistan has brought on serious dangers. There are numerous criminal groups included in the Taliban movement on the northern borders of this country right now. Some of them have also begun operating under the Islamic State flag, which has led to a sharp rise in the threat of terrorists invading Central Asia."

The Daily Express report said ISIS could be trying to open up a new front to the north of its territories after suffering reverses in Syria as a result of Russian airstrikes.

Such an invasion would be a slap on the face of Putin as it would take the ISIS into the former Soviet states of Turkmenistan, Uzbekistan and Tajikistan, which are still under Moscow's influence, the Express said.

If they succeed, the ISIS leaders would also secure control of lucrative drug trafficking routes, taking raw opium from Afghanistan to be sold as heroin on the streets of Russia and Europe, the publication warned.

Meanwhile, Russian jets continued pounding ISIS targets in Syria, destroying nine jihadist outposts including a command centre in just 24 hours using bunker-busting bombs, possibly killing dozens of fighters, according to Russian military officials.

Following the successful raids, Russian army spokesman Andrei Kartapolov vowed to further increase the pressure on the enemy, saying: "We will not only continue strikes... We will also increase their intensity."

Meanwhile, a terrorism expert called on Western leaders to launch a co-ordinated operation with the objective of completely destroying ISIS, saying that the ISIS have vastly exaggerated their military strength and are ready to go down if attacked with full force.

Dr. Afzal Ashraf said the ISIS has become its own worst enemy with its campaign of terror against the West, which has resulted in an international backlash.

"This mythical state will disappear in a matter of hours once the international community decides to act," he said.