MOSCOW (Reuters) - Russia, China and Pakistan warned on Tuesday that the influence of Islamic State (IS) was growing in Afghanistan and that the security situation there was deteriorating.

FILE PHOTO: An Islamic State flag is seen in this picture illustration taken February 18, 2016. REUTERS/Dado Ruvic/Illustration/File Photo

Representatives from the three countries, meeting in Moscow, also agreed to invite the Afghan government to such talks in the future, the Russian Foreign Ministry said.

“(The three countries) expressed particular concern about the rising activity in the country of extremist groups including the Afghan branch of IS,” ministry spokeswoman Maria Zakharova told reporters after the meeting.

The United States, which still has nearly 10,000 troops in Afghanistan more than 15 years after the Islamist Taliban were toppled by U.S.-backed Afghan forces, was not invited to the Moscow talks.

The gathering, the third in a series of consultations between Russia, China and Pakistan that has so far excluded Kabul, is likely to deepen worries in Washington that it is being sidelined in negotiations over Afghanistan’s future.

Officials in Kabul and Washington have said that Russia is deepening its ties with Taliban militants fighting the government, though Moscow has denied providing aid to the insurgents.

Zakharova said Russia, China and Pakistan had “noted the deterioration of the security situation (in Afghanistan)”.

The three countries agreed a “flexible approach to remove certain figures from sanctions lists as part of efforts to foster a peaceful dialogue between Kabul and the Taliban movement,” she added.

Afghan President Ashraf Ghani last month asked the United Nations to add the Taliban’s new leader to its sanctions list, further undermining a stalled peace process.

Earlier on Tuesday, Afghan Foreign Ministry Spokesman Ahmad Shekib Mostaghni said Kabul had not been properly briefed about the Moscow meeting.

“Discussion about the situation in Afghanistan, even if well-intentioned, in the absence of Afghans cannot help the real situation and also raises serious questions about the purpose of such meetings,” he said.

A number of Afghan provincial capitals have come under pressure from the Taliban this year while Afghan forces have been suffering high casualty rates, with more than 5,500 killed in the first eight months of 2016.

An offshoot of Islamic State has claimed responsibility for several attacks in the last year.