German Chancellor Angela Merkel and French President Emmanuel Macron expressed on Friday their solidarity with London over the poisoning of a former Russian spy in Britain. Meeting in Paris, Merkel said that Europe is looking for "the most appropriate response" to the attack that has been widely blamed on Moscow. Russia has denied the allegations. The European Union will hold a summit next week, with president Donald Tusk saying the bloc would send a "clear message". Macron, for his part, condemned "this Russian interference." He reiterated that "everything leads us to believe that is indeed Russia that was behind this attempted assassination." Macron evoked the "common will ... to forbid all forms of use of chemical weapons." Former double agent Sergei Skripal and his daughter Yulia were left critically ill by the attack in the city of Salisbury, southwestern England, on March 4. The German and French leaders also discussed EU reforms. Macron called for a "clear, ambitious" roadmap for the reforms by June as he sought crucial support for his shake-up of the bloc from Merkel. Merkel backed the deadline, telling a joint press conference: "We have to achieve results by June." Macron has called for a major reform drive to reinvigorate the EU, including a common eurozone finance minister and budget, but some European leaders have expressed reservations. The French president has been counting on support from Merkel, the leader of Europes biggest economy -- but nearly six months of politico limbo in Germany as she struggled to form a coalition government forced him to put his plans on hold. Flying into Paris for her first foreign trip since she was finally granted a fourth term Wednesday at the head of a hard-fought coalition, Merkel said the Franco-German relationship remained key for Europes future. "We do not always have the same opinions at first but France and Germany have accomplished a lot together in the past," she said. "We now want to find common paths ahead," she added. "I am determined to get there and I think we can do it. It is more necessary than ever that Europe be united in a geopolitical situation in which multilateralism is under pressure." Macron also said it was key for the EU to find a united way forward as it confronts a host of challenges including Brexit, migration and the rise of populism reflected most recently in the Italian elections. "This is our task by June: on the eurozone, on migration policy, defense, trade, research, education and large areas that we have been able to set out -- we will propose a clear, ambitious roadmap for this re-foundation by June." He congratulated Merkel on her new government, adding: "I have to tell you that the joy was all ours when it ended well."