The news comes just five days after Gatland unveiled controversial plans to designed to stop an "exodus" of leading talent from Wales.
The crux of Gatland's proposal was that any player who takes up a club contract outside Wales could be jeopardising his international future.
Gatland's plan has the full support of Welsh Rugby Union chief executive Roger Lewis and the four regions and is due to go before the full WRU board on January 24.
But even if the proposal is ratified, the WRU insist Peel's proposed move to Edgeley Park will not count against him because they were already aware it was in the pipeline.
Gatland said: "I will not penalise any of our current internationals who will not have been aware of the proposed new strategy until last week.
"It would be unfair as we are aware that Dwayne's negotiations were already well advanced when we made our statement.
"It is, however, important that all young Welsh rugby players know that we want to invest in them with the aim of realising that investment on the field for Wales.
"The structures and systems are being built here in Wales and we know we can nurture and develop the talent fully. We will do all we can to help the regions flourish."
Peel's move to Sale will end a 10-year association with Llanelli and the Scarlets.
The 26-year-old said: "My move's not about money as the deal to stay at Llanelli was similar to that offered by Sale - it's about the fact that, not having lived outside Wales, I'd like to experience life in another country for a short period."