Frank Hadden is not pleased at the absence of the players

Scotland head coach Frank Hadden hit out after three English-based players were prevented from joining a national squad training session on Tuesday.

Scrum-half Rory Lawson, winger Sean Lamont and lock Jim Hamilton were all refused permission to travel.

But Premier Rugby said it had aimed to be fair by "applying our policy across all nations".

Interview: Scotland coach Frank Hadden

Hadden claimed Premier Rugby's stance was hampering his preparations to face Italy.

But the PRL said its interpretation of the International Rugby Board's regulation 9.4 differed to the Scottish Rugby Union's.

The rule stipulates that a player selected for international duty who refuses or is unable to present himself will be barred from representing their club side for the duration he should have been with his country - plus another 10 days - unless his national union agree otherwise.

A PRL spokesman said: "We as a group of 12 clubs unanimously agreed that we would always allow the release of players during international Test weeks within IRB windows.

"We feel their (the SRU's) interpretation (of regulation 9.4) is that they're saying they should be allowed any player at 14 days notice.

"We think this gives them a 52-week window which is unfair and disproportionate.

"The only way we can make it fair is to apply our policy across all nations and that's what we have tried to do."

But Hadden said the move had hit his side's Six Nations plans.

"This decision taken by PRL at the highest level is most unhelpful for Scotland during our preparations for a vitally important Six Nations Test match against Italy," added Hadden.

"It also places an unfair burden on our three Exile players, who become piggy in the middle."

Hamilton plays for Leicester, Lamont for Northampton and Lawson for Gloucester.

And Hadden urged Scottish players who might be thinking about moving to English clubs in the future to consider the possible implications.