BERLIN - Chancellor Angela Merkel's cabinet agreed on Wednesday to expand the role of the German navy in the Mediterranean Sea to include efforts to stop arms headed to Islamic State militants in Libya, German Defense Minister Ursula von der Leyen said.The German decision comes days after the European Union gave its naval force the authority to search suspicious vessels as part of its five-frigate "Sophia" mission, which is also seeking to break up gangs smuggling migrants to Europe.Parliament is expected to approve the move before it adjourns for the summer at the end of June, according to government sources. The mandate also covers work to help Libya build up a coastal patrol and navy."We all have an interest in creating more order along the border to Europe," von der Leyen told reporters. "And it's important that the character of the mandate is being expanded to focus more on the root causes of the refugee streams."She said the expanded EU and German missions followed a U.N. decision to reinforce an arms embargo on Libya, where Islamic State fighters operate. "That sent a very strong signal," von der Leyen said.Germany has thus far participated in the EU mission with a logistics ship, and about 950 German soldiers have helped rescue about 15,000 people at sea since May 2015, according to the German military.Once approved by parliament, Wednesday's decision means German ships will be able to stop, search and seize larger vessels used by gangs transporting migrants, and also take suspects into custody, the sources said.In cases of suspected arms smuggling, they will also be able to search ships transiting to and from Libya, they added.Von der Leyen said there were still some legal issues to resolve regarding Germany's expanded role, but the cabinet decision and expected parliamentary approval would allow the German military to begin detailed planning for the bigger role.