India and Pakistan inched closer Friday to joining a regional security and economic bloc led by Russia and China, a move seen to boost the importance of the organisation.

"We expect that our partners will be able to accede as quickly as possible, by our next meeting in Kazakhstan" next year, Russian President Vladimir Putin said after the two countries signed memorandums on joining, the Kremlin website said.

Putin spoke at the summit in the Uzbek capital of Tashkent of the bloc known as the Shanghai Cooperation Organisation (SCO).

Putin added it was time to "work closely" on ensuring India and Pakistan are integrated into the organisation's cooperation mechanisms, which include regular meetings between member states' foreign ministers and heads of government.

Indian Prime Minister Narendra Modi thanked Putin for his "constructive role" in his country's bid to join SCO, after Putin had said India's accession would allow for closer cooperation between Moscow and New Delhi, the website said.

Putin told Chinese state news agency Xinhua ahead of the summit that the accession of India and Pakistan would increase the organisation's "relevance, both in the region and worldwide".

Uzbek president Islam Karim told local media Friday that the accession negotiations for Pakistan and India had been "difficult" but that organisation members had managed to reach a compromise.

The SCO -- whose members also include Kazakhstan, Kyrgyzstan and Tajikistan -- is mainly focused on security, although critics say it has done little to prepare the region's weaker states for potential fallout from instability in Afghanistan on the bloc's southern border.

Commentators have come to view the bloc as a vehicle for managing Russia and Chinese interests in Central Asia, which often appear to be at odds.

China is currently championing an ambitious plan to complete trade-boosting infrastructure projects, including land and sea links touted as a revival of the ancient Silk Road trade route.

Russia, in turn, has focused on broadening its protectionist Eurasian Economic Union integration project involving four of its former Soviet allies.

Putin also said at the Friday summit that there were "no obstacles" left for Iran -- currently an SCO observer -- to join the organisation now that sanctions connected to Tehran's nuclear programme have been lifted.

Turkey had also expressed a desire to join the SCO before its relations with Moscow soured over Ankara's downing of a Russian fighter jet used in Moscow's military operations in Syria last year.