The 24-year-old's deal expires at the end of the season and has been linked with a move to Premiership champions Saracens.
Other clubs would surely be interested in the former Wigan rugby league man too, with his prolific try-scoring ability establishing him as one of the leading wingers in the game.
Ashton, currently serving a four-week ban for pulling the hair of Leicester wing Alesana Tuilagi, has scored 90 tries for Saints since switching codes from Wigan in 2007, as well as racking up 15 tries in his 18 Test appearances.
Northampton are keen to hold on to the three-quarter but Mallinder told BBC Look East: "There's not an offer on the table, because his agent doesn't want
to talk to us.
"We've not had discussions and I think his mind is elsewhere. If he wanted to stay, we'd talk to him.
"If any player wants to go, for whatever reason, whether that's moving to London, or a massive financial offer, we're not going to stand in their way.
"We'll shake their hand and we'll get players who want to play for Northampton."
Northampton chairman Leon Barwell has previously stated that the club will not break the bank in order to keep hold of Ashton.
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The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
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