Wissa has made clear he desires to depart for St James’ Park and has not been coaching or enjoying with the primary crew this season.
In line with sources, Brentford initially needed £40m for Wissa however the value has now elevated to about £65m.
The switch window closes at 19:00 BST on Monday.
Brentford have already misplaced fellow ahead Bryan Mbeumo this summer season to Manchester United for £65m, however signed Dango Ouattara from Bournemouth for a membership document deal price as much as £42.5m.
Wissa’s potential transfer to Newcastle is believed to be a part of a sequence of transfers that would lead to Alexander Isak becoming a member of Liverpool.
Isak is in a related state of affairs at Newcastle, accusing the membership of “damaged guarantees” as he tries to power an exit to the Premier League champions.
In his assertion, Wissa – who has scored 49 objectives in 149 video games since he joined in 2021 – stated: “I’ve stayed silent for a lot of the summer season, however with simply hours remaining of the switch window I really feel compelled make it clear that I wish to go away Brentford. I consider the membership are unduly standing in my manner regardless of a sequence of truthful presents all through the summer season.
“This has left me in a troublesome and irritating place. It saddens me to have to put in writing that, and I keep whole respect for the membership and its followers.”
He added: “I ask Brentford’s house owners and administrators to now honour their promise to let me go away within the ultimate hours of the window.”
BBC Sport reported in July that Wissa flew house early from the membership’s summer season coaching camp in Portugal after making clear he needed the transfer to Newcastle.
Ever since he has been in a stand-off with the membership over his intention to affix Eddie Howe’s aspect.
He did return to first-team coaching for a brief interval however has gone again to working away from Keith Andrews’ squad.
Wissa, who scored 19 objectives within the Premier League final season, additionally eliminated all affiliation with Brentford from his Instagram account.
He says a proper supply was submitted by one other Premier League membership and he was “beneath the impression, from all my conversations with Brentford, that there was a mutual settlement to half methods”.
He added: “I wish to make it clear that I’ve not acted unprofessionally, nor do I want to go away Brentford on dangerous phrases. I’ve been clear in my place all through. I’ve continued to speak overtly with the membership and conduct myself in a manner that displays my values as each a footballer and a human being.
“Within the meantime, I need to do what I really feel is true for my profession and household and demand that Brentford honour their promise to let me be a part of a brand new membership and at a good value.”
BBC Sport has contacted Brentford for remark.
