Russia will take part in more drug raids in Afghanistan despite strong protests from the Afghan government, the Nato secretary-general has said.
Anders Fogh Rasmussen told the BBC such raids were allowed under a United Nations mandate.
Last week American and Russian drug control agents destroyed heroin laboratories in Afghanistan.
President Hamid Karzai said Russia's involvement was a violation of his country's sovereignty.
Speaking during a visit to Moscow on Wednesday, Mr Rasmussen told the BBC: "These activities will continue.
"Actually, we do have a far reaching co-operation with Russia when it comes to counter-narcotics and these operations take place within the mandate provided by the United Nations."
Last week's raid was the first such joint operation in Afghanistan involving the Russians. Russian involvement there has been increasing recently.
It was confirmed on Wednesday that Russia had sent the first of 16 planeloads of weapons to Kabul, which are being donated to the Afghan police force.
But Mr Rasmussen specifically ruled out any possibility of Russian troops getting involved in the war.
He said this was something that was wanted neither by Russia nor Afghanistan, where memories of the Soviet occupation in the 1980s are still raw.
Mr Rasmussen was in Moscow to make the final preparations for a Nato-Russia summit to be held in Portugal later this month. He held talks with Russian officials.
Both he and the Russian government say the summit will draw a line under the lingering suspicions which have hampered relations between the two former Cold War enemies.