WASHINGTON- US Treasury Secretary Jack Lew met with the emir of Qatar and emphasized the importance of fighting "terror financing," amid suspicions that money from one of the key U.S. Middle East allies had gone to violent extremists in the region."(Secretary Lew) ... emphasized the vital importance of combating the financing of terrorism," Treasury said in a statement. "(Lew) expressed his hope that in the coming months ... the two nations can continue to work together to take effective, lasting action to disrupt the activities of terrorist financiers."The emir of Qatar had previously met with US President Barack Obama and said he is committed to fighting Islamic State. Qatar is part of the US-led coalition fighting the extremist group.