PARIS, Feb 5 (Reuters) - France will summon Russia's ambassador on Monday after the death of two French humanitarian workers following a Russian strike in Ukraine, and what Paris said was an upsurge in Russian disinformation, a French diplomatic source said.

Two French volunteer aid workers were killed and another three wounded in a Russian drone attack in the southern Ukrainian region of Kherson on Feb 1 in what Foreign Minister Stephane Sejourne described as an act of "barbarity".

"France will reiterate its condemnation of the Russian strikes," said the diplomatic source. "It will also denounce an upsurge in disinformation targeting France."

Already frosty as the war in Ukraine nears its second anniversary, Franco-Russian relations have deteriorated further in recent weeks as Paris has increased its support to Ukraine, including promising to send more long-range cruise missiles.

It has accused Russia of habitually spreading false information. At the end of January it dismissed any notion that Paris had mercenaries operating in Ukraine a day after Russian lawmakers adopted a resolution condemning French 'mercenaries' in Ukraine.

It has also accused Russian President Vladimir Putin of relaying false information after suggesting missiles that had downed a Russian plane carrying Ukrainian prisoners of war could have been from a French air defence system.

The foreign ministry has warned of further Russian disinformation ahead of President Emmanuel Macron's visit to Ukraine later this month.

Just two days after he announced new weapons' deliveries on Jan. 16, Russia's defence ministry said its forces had killed some 60 French mercenaries in a strike on a building in Kharkiv.

It did not provide evidence to back the assertion and France rejected the allegations.