Clark and Hughes are likely to feature for Australia in the summer
England captain Andrew Strauss has joined in the criticism of some English counties for recruiting Australian players ahead of this year's Ashes.
Middlesex and Kent have signed Phillip Hughes and Stuart Clark respectively ahead of the series, starting in July.
"It would be better if they weren't playing, there's no doubt about that," Strauss told BBC Radio Five Live.
"It's very easy for the counties to be short-sighted and worry about their next championship game and season."
Playing in county cricket prior to the series will allow both players to acclimatise to English conditions, whilst also aiding Clark - Man of the Series in the 2006/07 Ashes - in his rehabilitation after undergoing elbow surgery in December.
If we hadn't signed Stuart, another county would have done - there is absolutely no doubt about that
Kent chief executive Paul Millman
Whilst Strauss expressed some sympathy for his own county Middlesex, who signed Hughes prior to his selection for the Australia side, he argued English counties should be geared towards helping out the national side as part of a mutually beneficial process.
"From an England team's point of view it's important we all need to buy into the fact that an England team performing well helps everyone, including the counties," he said.
"There is a bigger picture there and I urge all people running counties to realise an England side doing well is of paramount importance for the counties and England to thrive.
"You can't imagine Australia doing it for us so let's hope the counties learn lessons from this and we all pull together in what is an important year."
Former England captain Alec Stewart called for a curb on foreign players playing in county when their national side is touring England in the same season.
Stewart, who played 133 Tests for England in a 13-year career, told BBC Radio Five Live: "I'm totally against it.
"I would like to see a rule brought in which states overseas players cannot play (county matches) in our country if their side is touring that summer.
"It's wrong that we are giving Australia a helping hand in retaining the Ashes. It's tough enough anyway playing against them.
"But why we are giving them match practice and proving their fitness in our own domestic game is beyond me."
Stewart's sentiments are shared by England managing director Hugh Morris and national selector Geoff Miller.
"It's disappointing to hear Kent have signed a bowler who has played in English conditions before and is just coming back to fitness," said Miller.
"Middlesex have already signed a batsman in Phil Hughes who has not had experience of English conditions before and now will have that for the Ashes - I don't think this would happen the other way around."
Why we are giving them match practice and proving their fitness in our own domestic game is beyond me
Former England captain Alec Stewart
Although Middlesex director of cricket Angus Fraser sympathised with Miller, he dismissed claims that county spells would only serve to benefit Australia.
"England's cricketers haven't shone in Twenty20 but I don't hear India's BCCI (Board of Cricket and Control in India) complaining about England's cricketers getting Twenty20 practice ahead of the ICC World Twenty20 (in June)," he told BBC Five Live's Sportsweek.
And Kent chief executive Paul Millman defended the decision to sign Clark, arguing the county must balance national success with their own requirements.
"If we hadn't signed Stuart, another county would have done - there is absolutely no doubt about that," he said.
"It is possible this summer that we might not see a lot of England bowler Amjad Khan playing for Kent.
"That's great for English cricket and great for Amjad but it leaves a bit of a gap for us and we've got to think about how we fill that gap."