Nick D'Arcy and Kenrick Monk have arrived back in Australia amid suggestions they could be dumped from the Olympic squad for posting a photo of themselves brandishing guns on Facebook.

Both swimmers are facing serious sanctions after the photo, showing them posing with high-powered weapons in a US gun shop, was posted on Monk's Facebook site.

This morning the head of Australia's Olympics mission Nick Green told AM that the pair may have brought the entire squad into disrepute.

"It's a question that will get asked a lot around these two particular swimmers," he said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 2 minutes 47 seconds 2 m 47 s D'Arcy and Monk Olympic spots in doubt ( Samantha Donovan ) Download 1.3 MB

"Clearly what it has done is breach a social media guideline that we think is important.

"We will look at all the facts that are presented to us about [whether] is there any athlete that has breached the team agreement.

"One of the questions [we'll be asking] is have they brought themselves into disrepute, and have they bought the Australian team into disrepute?"

The photo was taken while D'Arcy and Monk were in California competing at the Santa Clara Grand Prix with other Australian team members earlier this week.

It was also circulated on Twitter before Swimming Australia ordered the Olympic-bound pair to take it down.

This morning D'Arcy told reporters at Brisbane airport that he "deeply apologised" for any offence caused.

He said he and Monk had visited a shooting range and "got the opportunity to fire a couple of guns, which was pretty fantastic to be honest."

"It was all meant to be a bit of fun, the photos were a bit of fun, and if anyone's been offended, obviously I deeply apologise," he added.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 4 seconds 1 m 4 s Nick D'Arcy says sorry over gun stunt

"It was never supposed to be offensive, and as I say, deeply sorry to anyone who was offended."

It is not the first time the two swimmers have found themselves in trouble.

In 2008, D'Arcy was taken to court for king-hitting team-mate Simon Cowley, while last year, Monk falsely claimed he was the victim of a hit-run accident after falling off his skateboard.

Swimming Australia is continuing to investigate the incident but ordered the photo to be removed in accordance with the take-down clause in its social media guidelines.

Swimming Australia says it will be speaking to D'Arcy and Monk later today.

D'Arcy, 24, was a controversial selection for the 2012 Australian swimming team.

He was kicked off the 2008 team after he was charged with and eventually convicted of assaulting Cowley.

D'Arcy qualified for the London Olympics by winning the 200m butterfly at the national titles, but his position in the team was questioned by many as he had not cleared his debt to Cowley.

A judge in a civil hearing last year ordered D'arcy to pay Cowley $370,000 in damages and costs but D'arcy subsequently declared himself bankrupt.

Monk also tarnished his reputation when he admitted last year to making up a hit-and-run story to explain his injured arm.

He confessed that he actually broke his elbow falling off a skateboard.

Monk said he had made up the hit-and-run story because he was not supposed to be engaging in dangerous sports.

Monk, also 24, claimed a relay spot in the Olympic team when finishing third in the 200m freestyle at the Australian titles.

He admitted after the selection trials that he still has trouble straightening his arm as a result of the skateboard accident.