A US online retailer has been reprimanded for promoting an explicit ad for a penis extender strap within video games played by children.

UK watchdog the Advertising Standards Authority (ASA) said that Wish.com had behaved "irresponsibly" and must ensure its adverts were properly targeted at appropriate age groups in the future.

It marks the third time in five months that the San Francisco-based firm has been found to have breached the rules.

In each case it has failed to respond.

The powers the ASA has to punish offenders are limited, but it told the BBC it would "continue to apply pressure on Wish.com where necessary".

The latest ruling concerns an advert that appeared on 26 November.

It showed an animated image of a penis above a second animation of the strap being applied.

Members of the public reported seeing the imagery in two puzzle-themed apps: Zynga's Crazy Cake Swap and Ketchapp's 2048.

Both have a Pegi 3 rating, meaning they had been judged to be suitable for all ages by Europe's video games ratings authority.

In addition, the ad was also spotted in Peel Smart Remote, a TV remote control app.

Ketchapp said it believed that it should not be held responsible for ads served up in its software, but added that it had increased the age rating of all of its games in response to the complaint.

The ASA said that Zynga did not respond to its inquiries while Peel Technologies' reply was not substantive.

"We considered that given the content of the apps, they were likely to have a broad appeal to all ages including children," the watchdog's ruling stated.

"The ad must not appear again in an untargeted medium."

Wish did not reply to the BBC's request for comment.

Unzipped clothes
The ruling comes just a week after the ASA upheld other complaints made against Wish and its parent Contextlogic.

These followed its promotion of adverts featuring a baby wearing ripped shorts that exposed its bottom "for no reason that was relevant to the product".

In some cases the photo appeared alongside a picture of a woman wearing an unzipped cat suit, who was also exposing parts of her buttocks.

These adverts had appeared on Facebook as well as an unidentified app, and were judged to be "offensive".

Prior to this, the ASA criticised Wish in November for an ad featuring a "red and bloody" temporary tattoo placed on a woman's shoulder.

It had appeared in the game Simon's Cat Crunch Time last July.

The authority said that children who had seen it might have suffered distress.

The ASA does not have the power to impose fines.

However, it told the BBC it had taken other action to tackle the problem.

"In all three rulings against Wish.com, we have directly contacted the media owners and planners who have been involved in the placement of Wish.com's ads," a spokeswoman told the BBC.

"We have since received assurances from these media owners and planners that they will either refuse future advertising from Wish.com or adapt their processes to ensure more appropriate ad targeting."