* French leader discusses Ukraine separately with Obama and Putin
* Hollande working to get Putin, Ukrainian leader to meet on D-Day
Hollande, criticised at home for a lack of initiative on Ukraine, had a working dinner with U.S. President Barack Obama before dashing across Paris to join Russia's Vladimir Putin for a second evening meal.
Hollande and Obama discussed "how to use opportunities in the coming days to bring about a de-escalation," a member of Hollande's entourage said following the meal.
One of Hollande's main aims, diplomats said, is to clear the path for an ice-breaking first meeting on French soil on Friday between Putin and Ukrainian president-elect Petro Poroshenko, even as fighting in eastern Ukraine continues between government forces and pro-Russian separatists.
The separate meals showed the lengths to which French officials have gone to keep Obama and Putin apart in Paris, at Washington's request, before Friday's commemorations of the Allied D-Day landings that helped end World War Two, which will see 18 world leaders assemble on the Normandy beaches.
The French capital went into security lockdown before Britain's Queen Elizabeth arrived by train from London. She was followed by Obama, who flew in from a Group of Seven (G7) meeting in Brussels to which Putin had not been invited.
"This is an important occasion to express gratitude and fraternity, but it is also major international event which should serve the interests of peace," Hollande told the G7 summit before he too rushed back to Paris.
Asked if a Putin-Poroshenko meeting in France was possible, Hollande replied: "Yes ... I invited (Poroshenko) so he could be there, because he represents the Ukrainian people who suffered a lot during World War Two. He will be there alongside President Putin. President Putin was informed of that."
Obama called on Putin to recognise and work with Ukraine's new government and stop "provocations" along its border, or face tougher sanctions from members of the G7.
Highlighting shades of difference among Western stances on Russia, Obama told reporters he would have preferred France to have held back on the sale of Mistral helicopter carriers to Russia that Paris has insisted must go ahead.
"I recognise that the jobs in France are important," Obama said. "I think it would have been preferable to press the pause button."
Putin said in French media interviews on Wednesday he was open to meetings with both Poroshenko and Obama in France.
But underscoring the sensitivities, Hollande rushed from meeting the Queen at Elysee Palace to a chic restaurant overlooking the Champs-Elysees to dine with Obama, before returning to his residence for a late supper with Putin.
For Hollande, the Obama dinner was also the opportunity to raise concerns about a possible $10 billion-plus U.S. fine on BNP Paribas that he considers "disproportionate".
Hollande has spent much of the week trying to create a diplomatic opening on Ukraine after sending Poroshenko a last-minute invitation to the D-Day ceremonies. Ukrainians fought in the Soviet Red Army that defeated Nazi Germany.
French diplomats say Hollande, who met Poroshenko in Poland on Wednesday, wants at the very least to get Putin and the Ukrainian to shake hands at a closed-door lunch of leaders on Friday at the 18th-century Chateau de Benouville.
This, they argue, would be a tacit acknowledgement that the Russian leader recognises Poroshenko's legitimacy, the day before he is sworn in, opening the door for dialogue.
In an apparent signal of recognition, Russia's deputy foreign minister, Grigory Karasin, said Moscow's ambassador to Ukraine would attend Poroshenko's inauguration.
Russian Foreign Minister Sergei Lavrov told reporters after meeting with his counterpart John Kerry on Thursday that the United States should press Poroshenko to stop violence and talk to separatists, Russian media reported.
Earlier in the day, Lavrov said Russia wanted "Ukraine peaceful and stable for all those who live in Ukraine."
Putin did not rule out a first encounter with a pro-Western Ukrainian leader since Moscow annexed the Crimea in March.
"You know, I don't plan to evade anyone," Putin told TF1 television on Wednesday when asked if he was willing to meet Poroshenko. "There will be other guests, and I'm not going to avoid any of them. I will talk with all of them."
His relations with Ukraine, the European Union and the United States have been strained since pro-Western protesters pushed a Moscow-friendly Ukrainian president from power in February and Russia then annexed Crimea.
Moscow has deployed tens of thousands of troops near the Ukrainian border, warning it could deploy them to protect Russian speakers as Ukraine's government has ignored Moscow's demand to end Kiev's military operation against the separatists.