Israeli Prime Minister Benjamin Netanyahu sought Britain's cooperation to "turn back the tide of militant Islam" as he met Prime Minister David Cameron in London.
Ukrainian Prime Minister Arseniy Yatsenyuk criticised as "anti-Ukrainian and anti-European" a deal between Russia's energy giant Gazprom and several Western firms to build a second gas pipeline under the Baltic Sea.
Chancellor Angela Merkel won a hero's welcome as she visited a Berlin migrant centre, with Syrians cheering and taking selfies as Germany threw open its doors to thousands of refugees.
Around 450,000 refugees have arrived in Germany so far this year, including 37,000 in the first eight days of September, Vice Chancellor Sigmar Gabriel told parliament.
Catalan separatists hold a massive rally in Barcelona in favour of independence that will kick off campaigning for a regional election billed as a de facto referendum on secession from Spain.
Hundreds of migrants broke through police lines in Hungary near the Serbian border for a third day running, as the army began mobilising for a possible role in guarding the frontier.
Britain celebrated Queen Elizabeth II becoming the country's longest-reigning monarch, a milestone the 89-year-old herself downplayed as "not one to which I have ever aspired."
Ukrainian Prime Minister Arseniy Yatsenyuk warned that any attempt to hold "unlawful" elections in rebel-run areas in the country's east would constitute a breach of a February peace deal.
A first group of around 50 refugees arrived in France from Germany as Paris tries to ease pressure on its neighbour, which has received the bulk of the migrants streaming into Europe.
After reigning through the decline of the British empire and some of the worst scandals in royal history, Queen Elizabeth II is set to become Britain's longest-serving monarch.
EU president Donald Tusk urged a crackdown on the "murderers" among human traffickers who have killed scores of people trying to reach Europe from conflicts abroad.
The United States has asked Greece to ban Russian supply flights to Syria from its airspace, amid growing US fears that Moscow is increasing its military backing for Syrian President Bashar al-Assad.
British Prime Minister David Cameron suffered an embarrassing defeat in parliament over how the referendum he has called on leaving the European Union will be conducted.
The Greek island of Lesbos is "on the verge of explosion" with violence erupting as the more than 15,000 mainly Syrian refugees push local resources to the limit.