Brussels, Jumada I 7, 1437, Feb 16, 2016, SPA -- A number of "unsolved problems" remain in the negotiations on reforms demanded by Britain ahead of its in-out referendum, EU President Donald Tusk said Tuesday, as he wrapped up a whirlwind European tour meant to win over other member states, dpa reported. "I have no doubts: there is an extra mile we will have to walk to reach an agreement," he said in Prague after meeting Czech Prime Minister Bohuslav Sobotka. "There are still unsolved problems." EU leaders will attempt later this week to strike a deal on the reforms, which British Prime Minister David Cameron has said would allow him to campaign for his country to remain an EU member. He has promised to hold a referendum on the matter by the end of 2017. -- SPA 21:50 LOCAL TIME 18:50 GMT www.spa.gov.sa/w