The game was played on one of the hottest days Britain has recorded

Six AMs went to last August's Manchester United - Arsenal Community Shield match at McDonald's invitation, but only two of them declared it on the assembly's register of interests, including Welsh Sports Minister Alun Pugh.

That led to Labour accusing the Tories of "absolute rank hypocrisy" for criticising Mr Pugh, when two Conservative AMs had also gone, and they had failed to register.

Mr Pugh had registered his McDonald's hospitality and said he was happy to talk to the firm, but the Tories said he still should have turned it down because he was campaigning against child obesity.

The Conservatives highlighted the issue on the day Labour MP Jon Owen Jones launched an attempt to ban school vending machines from selling junk food.

The six AMs who had McDonald's hospitality at the game in Cardiff were: Tories Alun Cairns and Glyn Davies, Labour's Alun Pugh, John Griffiths and Brian Gibbons, and Plaid Cymru's Rhodri Glyn Thomas.

Only two AMs, both Labour, registered their hospitality as required under assembly rules: Mr Pugh and Mr Griffiths.

Alun Cairns has apologised for failing to register

The hospitality was part of a weekend of events, culminating in the McDonald's-sponsored fund-raising AMs v MPs football match the day before the Community Shield.

Nick Bourne, leader of the Tories in the assembly, said there was clear evidence that an unhealthy lifestyle, including eating fast food, was the primary cause of obesity, and Mr Pugh should have turned down his invitation on a point of principle.

But it is understood that Mr Cairns, AM for South Wales West, has now written to assembly Presiding Officer Dafydd Elis-Thomas to apologise for failing to register his own presence.

Fellow Conservative Glyn Davies, AM for Mid and West Wales, said his own failure to register may have been due to a mix-up in his office.

AMs saw Arsenal's Thierry Henry score in a game won by Man Utd

Mr Davies said if he should have declared, he would also apologise and register it immediately.

But Mr Davies also said he was quite happy to accept the hospitality, he believed McDonald's was doing a lot of good work in promoting sport for children, and dissociated himself from the attack on Mr Pugh.

A spokesman for the Conservative assembly group said it stood by its assertion that Mr Pugh should have declined the hospitality invitation, as it believed association with a fast food chain was not compatible with a campaign for a healthy lifestyle.

But a spokeswoman for Mr Pugh said it was "absolute rank hypocrisy" for the Conservatives still to be making an issue of this.

She said Mr Pugh had never said people should not eat a burger as part of a healthy lifestyle.

The minister got involved in this instance, she said, because McDonald's had supported grassroots football by providing a grant to the Football Association of Wales to increase the number of coaches at community level, and because there was a charity game to support Truce, which backed soccer in the Third World.

She said it was "ludicrous" for Tories to complain when their own AMs had also taken hospitality and, unlike Mr Pugh, failed to declare it.

Plaid's Mr Thomas, AM for Carmarthen East and Dinefwr, said he did not register because he did not believe it was of enough value, but if it was he would also apologise and register it.

A spokesman for Dr Gibbons, AM for Aberavon, said he did not know at the time that the hospitality was being paid for by McDonald's, still did not know how much it was worth, but it was of enough value, he would register it.