Ministry officials have launched an investigation after complaints that a low-flying military jet disrupted the first worldwide sheepdog trials.

Organisers are said to be "livid", claiming that a plane circled the trials site in Bala, north Wales.

The pilot seemed to be deliberately circling above the site

Norman Lorton, International Sheep Dog Society

It happened, they said, despite Ministry of Defence assurances that low-flying exercises would be suspended during the contest.

An MoD spokeswoman revealed on Friday that investigations had begun into allegations that one of its aircraft may not have respected the temporary avoidance area.

"Should that be the case then we are very sorry, and trust that there was no disadvantage to anyone," she said.

"This will be treated extremely seriously."

The apparent blunder happened on the opening day of the World Sheepdog Trials, which have attracted 130 dogs from 13 countries.

Dogs from 13 countries attended the trials

Norman Lorton, chief executive of the International Sheep Dog Society "We're livid. The pilot seemed to be deliberately circling above the site.

"The jet blatantly disregarded the exclusion request and when he finally eventually decided to fly off the noise was absolutely deafening."

Organisers say a member of the French contingent was forced to abandon her qualifying routine as the jet flew overhead.

She was granted a re-run following consultations with the International Sheep Dog Society.

This will be treated extremely seriously

MoD spokeswoman

Annie Le Roux, 42, of Roscoff, Brittany, said: "I was very disappointed when I was interrupted by the jet. It was enough to make Ladji the dog disorientated and he failed to perform to form on the second attempt."

Despite the noisy disruption organisers hailed the opening day of the event an overwhelming success with more than 2,000 people converging on the Rhiwlas estate for the qualifying rounds.

"We are delighted with the numbers that came through the gate," said event organiser Ruth Frazer.

"With the weekend coming up we're well on course to make the first world sheepdog trials a resounding success."

The winning national team is expected to be announced at the end of Friday, following further qualifying rounds.

The semi-finals will be staged on Saturday with the remaining 16 dogs competing on Sunday for the top prize.