David Weir makes heart-rending apology for Rio performance on Twitter

Updated: 

David Weir has  taken to Twitter to apologise and voice his frustration after a series of disappointing performances at his last Paralympics.

The six-time gold medallist came fourth, fifth and sixth in the 1500m,  400m and 800m T54 races respectively .

David Weird during the mens 800m T54 race (Adam Davy/PA)

In the tweet posted on Friday evening, he explained that he didn't know what went wrong, and lamented that  "I've missed my sons (sic) birth for this terrible performance, but I gave what I could.

"I'm deeply sorry I've let the country and my team mates down."

The 37-year-old wheelchair racer won four gold medals from four events at London 2012, but could leave Rio 2016, his fifth and final Paralympics, with nothing, unless he achieves a podium place in Sunday's marathon.