President Asif Ali Zardari left Washington Saturday evening at the conclusion of his visit, during which he discussed bilateral relations with U.S. President Barack Obama and attended a memorial service for Richard Holbrooke. Zardari is on his way to United Arab Emirates for a global energy summit, to be attended by several world leaders. The Pakistani leader also had the opportunity to discuss support for his countrys anti-polio campaign, when business magnate and founder of Bill and Melinda Gates Foundation, Bill Gates, called on him and also offered to help Pakistan in immunization of children against several diseases. On Friday, President Obama had received President Zardari to discuss cooperation in economic and counterterrorism areas and voiced White Houses strong backing for democracy in the country. Secretary of State Hillary Clinton also attended the meeting. Zardari also attended a memorial held at the Kennedy Center to pay respect to memory and work of Richard Holbrooke, who was serving as U.S. Special Representative for Pakistan and Afghanistan until his death in December last year. Congresswoman Sheila Jackson-Lee and Congressman Chris Van Hollen also called on President Zardari during his stay in Washington. Presidential Spokesman Farhatullah Babar and Pakistans Ambassador to the United States Husain Haqqani accompanied the president during his meetings. UAE Foreign Minister Shaikh Abdullah bin Zayed al-Nahyan also paid a courtesy call on President Zardari on Saturday.