UNITED NATIONS, United States: Russia told a closed-door UN Security Council meeting on Friday that it opposed a 30-day extension of an investigation to determine who is behind chemical weapons attacks in Syria, diplomats said.

The council met a day after Russia vetoed a US-drafted resolution to renew for one year the mandate of the UN-led Joint Investigative Mechanism (JIM).

Japan on Thursday presented a draft resolution that would give the JIM a 30-day extension to allow for negotiations on a compromise to salvage the panel.

But Russia's Deputy Ambassador Vladimir Safronkov told the council that Moscow "will not accept the Japanese draft," said a diplomat attending the closed session.

The council was still meeting to decide on the way forward and whether the draft resolution would be put to a vote.

The Japanese proposal came after a Russian veto -- Moscow's 10th on Syria -- while a separate Russian draft resolution failed to garner enough votes for adoption.

"This is a way to avoid the death of the JIM, a way to give us time to think seriously about a lasting solution," French Ambassador Francois Delattre told reporters ahead the meeting.

The Russian measure would have also extended the JIM but also demanded a new investigation of the Khan Sheikhun attack.

Russia has strongly criticized the JIM after its latest report blamed the Syrian air force for a sarin gas attack on the opposition-held village of Khan Sheikhun that left scores dead.

The attack on April 4 triggered global outrage as images of dying children were shown worldwide, prompting the United States to launch missile strikes on a Syrian air base a few days later.

Syria has denied using chemical weapons, with strong backing from its main ally Russia.

The Japanese draft resolution would renew the JIM mandate for 30 days and task UN Secretary-General Antonio Guterres with submitting to the council in 20 days "proposals for the structure and methodology" of the panel.

The joint UN-Organisation for the Prohibition of Chemical Weapons (OPCW) panel was set up by Russia and the United States in 2015 and unanimously endorsed by the council, which renewed its mandate last year.

The expert team is tasked with determining who is responsible for the use of chemical weapons in Syria.