Both have been influential players over the last two seasons with Roets, who is playing rugby union with Welsh Premiership side Tonmawr in their 2011-12 season, missing just the one game and winning club awards in both 2010 and 2011.
Scorpions’ chairman Phil Davies said: “I am very disappointed that we haven’t been able to work out new deals with Christiaan and Aled. Taking into account their appearances in the recent Four Nations tournament for Wales, both were offered improved contracts from 2011. We couldn’t have gone any higher as we have a budget to stick to and we don’t want to go the same route as other clubs have done in the past!
“Both would have been influential players for us in 2012 as we look for promotion to the Championship, especially to our younger players, but unfortunately we couldn’t have done any more to try to secure their services. I’d like to wish both players luck in their future careers.
“We are rebuilding for 2012 after a disappointing season last year. We have already announced six exciting new signings and we will be announcing more in the next couple of weeks as we carry on building a new entertaining squad for 2012.”