Colin Jackson, with the union and Welsh flags at the World Championships in 1993
A long-standing rule banning athletes waving unofficial flags at the Olympic Games has been criticised by politicians in Wales.
According to an International Olympic Committee (IOC) rule, competitors should not have flags which could be perceived as a "political gesture".
This means the flags of Wales, England, Scotland and Northern Ireland are effectively banned.
Team GB will be represented by the union flag.
Also in the house rules for spectators on the games website, supporters are asked not to bring to arenas "flags of non-members of the Olympics or Paralympics".
A spokesman for the British Olympic Association said the rule was set out in guidelines.
He said: "This is a International Olympic Committee (IOC) guideline under rule 51 of the charter which states that flags which can be interpreted as a political gesture are not allowed inside any Olympic venues.
"...and as such only flags which participate in the Olympic Games are allowed by the IOC."
Amnesty International claims the measure is to ensure no flags of Tibet are displayed by campaigners.
Politicians from all sides have voiced their concerns over the flag-waving.
A Welsh Assembly Government spokesperson said: "The minister for heritage believes that Welsh athletes should be able to fly the Welsh flag on a lap of honour if they wish."
Conservative sport spokesman Paul Davies said: "This has serious implications for freedom of expression and the rights of supporters and athletes to celebrate their success.
"Welsh medal-winning athletes and their supporters have been able to wave the Welsh flag at previous Olympics without the threat of having them confiscated."
Plaid Cymru AM Chris Franks also expressed his concern over the rule which might prevent fans of Welsh athletes such as Nicole Cooke and David Davies from waving the Welsh dragon inside Olympic venues.