"Prior will continue to be assessed during the training session before a decision is made about his fitness," the England and Wales Cricket Board said in a statement.
Wicketkeeper-batsman Prior, who spent the first part of the season battling an Achilles injury, recently scored 86 against the visiting Sri Lankan's at Lord's but had a tough time behind the stumps at Headingley. He was brought into the side after being dropped post the third Test against Australia at Perth -- during the 0-5 Ashes drubbing.
However, Buttler and the England management have said that the batsman needs more time in first-class cricket to mature as a player. He has had a good County season for Lancashire with 491 runs at 40.91, which included one hundred and four fifties.
Buttler had recently said that he is satisfied with his batting but needs to work on his glovework.
"The move to Lancashire has been going okay for me and given me the opportunity to develop my wicketkeeping a bit faster than before. But I have to be realistic. It is my first season keeping as a first choice keeper in red ball cricket and I have to remember that and not get frustrated that I'm not quite doing it as well as I would like to yet.