Fired US Secretary of State Rex Tillerson has called Washington a "very mean-spirited town" as he took veiled potshots at his former boss President Donald Trump in his farewell address to his staff. Trump announced the sacking of Tillerson last week by tweet and named CIA Director Mike Pompeo as his successor. Tillerson mentioned Trump only once in his remarks, in passing and not by name, as he told staffers about preparing background materials "that were first the basis for discussions at the National Security Council and ultimately with the President." Tillerson in his brief speech yesterday ahead of his official departure at the end of the month, told State Department employees to hold on to their integrity. "It belongs to you," Tillerson said. "Only you can relinquish it or allow it to be compromised." When the 66-year-old former ExxonMobil CEO observed that Washington can be a mean-spirited place, foreign service officers and civil servants burst into laughter and applause, with many nodding. When he followed that up with the advice that people don't have to participate "in that," he was again interrupted by clapping. "I'd like to ask that each of you undertake to ensure one act of kindness each day towards another person," Tillerson said. He urged the employees to "treat each other with respect," adding that "we're all just human beings trying to do our part." "Each of us get to choose the person we want to be, and the way we want to be treated, and the way we will treat others," the veteran Texan oilman said. Tillerson said the country faces many challenges - in some instances perplexing foreign affairs relationships, and in other instances serious national security threats. "In these times, your continued diligence and devotion to the State Department's mission has never been more necessary," he said. Tillerson got sustained applause from staff, who clapped solidly for many minutes after Tillerson finished his remarks and while he slowly worked his way toward the exit, shaking dozens of hands as he departed, CNN reported. His leadership at State Department was characterised by often public friction with the White House and the President himself over staffing and policy, it said. Trump very publicly took a different stance than Tillerson on a dispute between Gulf nations, publicly mocked Tillerson's diplomatic efforts with North Korea, and disagreed with his top diplomat on how to approach Iran. With his call to State Department employees to treat each other with respect, Tillerson appeared to distance himself from Trump on issues of behaviour and the treatment of others.