Boston: US President Barack Obama's speech on late Sunday night announcing world's most wanted terrorist Osama bin Laden's death was watched by over 56 million people, making it the biggest TV audience for US President Barack Obama so far.

According to estimates by Nielsen Co, 56.6 million viewers watched the 9 minute speech, which was aired live on networks ABC, CBS, NBC, Telemundo, Univision, CNN, Fox News Channel, HLN and MSNBC.

Nielsen said despite the late hour and sudden alert from the White House that the President will be making a statement, Sunday night's audience was larger than recent prime-time addresses by Obama, including his March 28 speech on Libya.

Obama began his speech around 11:35 p m (as per time on the US East Coast) on May 1. It was the President's biggest TV audience since he was elected and was watched by 57 per cent of US households.

His speech in August 2010 on Iraq had over 29 million viewers, while his December 2009 address on Afghanistan was viewed by 40.8 million, Nielsen said.

Britain's Royal Wedding on Friday drew an average of 22.8 million viewers per minute.