Published Tuesday, 17 September 2013
Prime Minister David Cameron at the Lion members outside No 10. (© PA)
Manu Tuilagi, who plays centre for England, made a " bunny ears" gesture above the back of Mr Cameron's head during a photo shoot of players and management at the function held to honour the Lions' victory over Australia.
He later took to the social networking site to express his remorse, posting: "Apologies for messing around on Lions photo. No offence intended. Great Day at Downing Street. Thanks to Prime Minister for hosting us."
Mr Cameron welcomed the victorious British and Irish Lions rugby squad for the reception on Monday, when he was presented with fly-half Jonny Sexton's number 10 jersey.
He said: "It's a huge honour. My son, just because of you guys, has just started tag rugby. He will be so excited about this jersey."
The PM congratulated captain Sam Warburton and coach Warren Gatland as they brought along the Tom Richards Cup to Number 10.
The Lions, comprised of players from Wales, England, Scotland and Ireland, won the first and third tests to secure a 2-1 triumph in the three-match series with Australia during the summer.
It is not the first time Tuilagi has been the centre of controversy as he was fined £3,000 by the Rugby Football Union after he jumped from a ferry during England's World Cup campaign in New Zealand two years ago.
He was cautioned by police on that occasion and disciplined by then England coach Martin Johnson.
© UTV News