MOSCOW - The Russian Foreign Ministry has asked the international agency that monitors chemical weapons for information about the investigation of the poisoning of a former Russian spy and his daughter in England.

A list of questions submitted to the Organization for the Prohibition of Chemical Weapons includes what sort of assistance Britain requested from the watchdog agency and which sampling procedures were used to collect the substance that sickened Sergei Skripal and his daughter, Yulia.

OPCW representatives were among a group of experts Britain asked to analyze the chemical agent involved in the poisonings. Britain claims it was the Soviet-manufactured nerve agent Novichok and has said Russia is likely responsible, which Moscow adamantly denies.

The Russian Foreign Ministry's request came on the same day that Russian diplomats and their families returned to Moscow on two planes after being expelled from the United States, part of the international fallout from the March 4 attack on the Skripals.

Following a wave of similar expulsions ordered by Britain and numerous allies, the US ordered 60 Russian diplomats out of the country. Moscow responded by sending home 60 US diplomats and closing Washington's consulate in Saint Petersburg on Saturday.

Diplomats return

Russian news agencies said these 60 Russian diplomats and their families and returned on two flights that landed on Sunday at Moscow's Vnukovo Airport.

One carried diplomats from the Russian embassy in Washington; aboard the other were diplomats from the Russian consulate in New York and Russia's United Nations mission.

More than two dozen countries and NATO have expelled Russian diplomats in support of Britain. More than 150 Russian diplomats have now been ordered out of the US, EU members, NATO countries and other nations.

Four of those diplomats were sent home from Germany, whose foreign minister said on Sunday that his country remained open to dialogue and hoped eventually to rebuild trust with Moscow.

Heiko Maas said "we need Russia as a partner".

Russia has ordered an equal number of most of those countries' diplomats to leave and for Britain to reduce the staff at its Moscow embassy to the same number that Russia maintains in London.

Russia consistently has complained that Britain has not provided evidence to back up its claim of Russian involvement or that the poison that afflicted the Skripals was a Russia-developed nerve agent.

The Russian Foreign Ministry also submitted questions to British and French authorities on Saturday. The ministry did not say what actions Russia might take if the parties do not answer the questions or provide partial responses.

Ap - Afp