UNITED NATIONS - UN Secretary-General António Guterres strongly condemned on Monday air strikes on a wedding party in Yemen that killed at least 50 civilians, his spokesman said. Air strikes by a Saudi-led military coalition killed at least 20 people attending a wedding in a village in northwestern Yemen late on Sunday, residents and medical sources said. 'The Secretary-General reminds all parties of their obligations under international humanitarian law concerning the protection of civilians and civilian infrastructure during armed conflicts. He calls for a prompt, effective and transparent investigation,' UN spokesman Stephane Dujarric said in a statement.