First Minister Rhodri Morgan has denied that his failure to greet the Queen on her arrival at the Royal Welsh Show was a "faux pas".
Mr Morgan was caught in traffic on his way to the showground at Llanelwedd, mid Wales, and had to get out of his car to walk the final 100 yards.
Opposition parties have criticised Mr Morgan for failing to greet the Queen.
But the first minister's spokeswoman later said that the Queen had arrived early and Mr Morgan had been on time.
The Queen arrived at the showground at about 1000 BST on Wednesday and was welcomed to the centenary show by a party minus Mr Morgan.
The first minister later met up with the royal party.
Speaking to BBC Radio Wales, the first minister said his journey from Cardiff had taken an extra 15
minutes which had accounted for his late arrival.
"It's very difficult when the show is as popular as it is and you try and judge the time," he said.
Rhodri Morgan later caught up with the royal party
"It took 15 minutes longer today (than Monday) and then I had a very difficult decision.
"We had 100 yards to go and we thought 'right - we are going to try and run it from here'.
"Actually it would have been much better to stay in the car because as soon as we got out of the car, it started moving forward.
"It just one of those things. It was just impossible."
Asked if he had apologised to the Queen, Mr Morgan said he did not know whether she had noticed his absence from the welcoming party.
He added: "If I was aware that she knew, then of course I would have.
"But I don't know whether she would have noticed."
Asked whether it was a faux pas, he denied it. "Because the show is incredibly popular, it took 15 minutes longer than on Monday and it's as simple as that.
"I think she (the Queen) had a wonderful day.
"The show has been wonderful and anybody who tries to spoil a day like today and a 100th anniversary has got a very tiny mind."
But opposition parties at the Welsh assembly were critical, and some compared it to the controversy over his decision not to attend the 60th anniversary of D-Day in Normandy last month.
Mr Morgan sent another minister in his place while he was at a pre-arranged meeting at the Celtic Manor Resort in Newport to discuss golf's Ryder Cup, which is coming to Wales in 2010.
Nick Bourne, who leads the Conservatives in the assembly, said: "The first minister's behaviour is a gross insult to the Queen and a major embarrassment for the people of Wales who he is supposed to represent.
"The first minister should have made sure he left for the event in good time to guarantee he was there to meet the Queen.
"Rhodri Morgan should apologise immediately."
Ieuan Wyn Jones, leader of Plaid Cymru in the assembly, said: "I think that members of the Labour group in the assembly should have a whip round to buy the first minister an alarm clock to prevent any further embarrassment.
"This is the latest in a series of gaffes that have seen Mr Morgan let down Wales."
Liberal Democrat assembly leader Mike German said: "This is yet another disappointing misjudgement by Rhodri Morgan following on from the D-Day debacle.
"Everyone knows that the traffic around the showground is busy and most people with important appointments to meet allow extra travel time.
"I'm sure he didn't mean to be discourteous, but episodes like this one do nothing to enhance the image of Wales."
Mr Morgan's spokeswoman later said: "We've confirmed with the Royal
Welsh organisers that the Queen actually arrived early and took everyone by
surprise. So we were here on time."