Former US President, Barack Obama Tuesday recounted his biggest regret in office.

He said not being able to overhaul gun laws in the wake of one of America‘s most deadly school shooting was one of his biggest regrets and low points from his time in office.

His comments came just a day after another devastating shooting in the US where three children and three staff members at Nashville’s The Covenant School were killed.

The former US President also opened up on the need for gun control following the Sandy Hook massacre in 2012 where 26 people were killed, 20 of whom were children, while speaking at a leadership event in Sydney on Tuesday night.

‘That was the closest I came during my years in office to feeling very cynical about the capacity of politics, of people to join together to do what is obvious,’ he told the crowd at the International Convention Centre.

‘You run your race as best you can and you try to make a good handover and you have to take satisfaction from feeling as if you did the very best with the time allotted to you.

‘I think not changing the gun laws was an example of me trying very hard … but we could not budge Congress.’

Mr Obama has earlier said the day of the Sandy Hook Elementary School shooting was the ‘darkest day’ of his presidency, and added it was the only time he saw members of the Secret Service cry.

In the weeks after the attack, Mr Obama called on Congress to pass extensive reforms to the country’s gun laws, including banning assault weapons and guns with high-capacity magazines, and ramping up background checks on those buying guns.