31 March 1992
The United Nations (UN) imposed sanctions on Libya for refusing to hand over two men suspected of bombing the Pan Am flight 103. Seven years later (1999), after the UN passed a resolution to impose sanctions on the country, Libya turned over the Lockerbie suspects for trial, and sanctions were suspended. The story of the Pan Am flight 103 dates back to 21 December 1988, when a terrorist bomb exploded on board the plane, destroying the aircraft over the Scottish town of Lockerbie and killing 270 people, mostly Americans. In August 2009 the Libyan citizen arrested in connection with the blast, Abdelbaset al-Megrahi, was released from prison in Scotland. Upon his return he received a hero’s welcome from his countrymen at Tripoli Airport.In February 2011, after the outbreak of the revolution in Libya, the UN Security Council imposed travel and asset sanctions on Muammar Gaddafi and his closest aides.
References

Boddy-Evans A. ‘This Day in African History: 31 March’, from African History, [online], Available at www.africanhistory.about.com [Accessed: 23 February 2012]|The Guardian, (2009), ‘Lockerbie bombing: the aftermath’, from The Guardian, 21 August [online], Available at www.guardian.co.uk [Accessed: 23 February 2012]|Washington Post, ‘Gaddafi's 41-year-long rule’, from Washington Post, [online], Available at www.washingtonpost.com [Accessed: 23 February 2012]