"The World Cup this summer is a really big thing for me. I know that if I'm not playing regularly my chances of playing in South Africa will be badly affected.
"It would be my second World Cup and I want to get the best possible build-up to it.
"Unfortunately, I haven't played a lot of football recently and that's why I feel I have to leave Arsenal.
"Hopefully something will be in place over the next few days but I'll wait and see."
Celtic last week sold Gary Caldwell to Wigan, but have already signed another defender in Dutchman Jos Hooiveld, who arrived from AIK Stockholm, and the Glasgow club are understood to be close to concluding a deal for Norwegian stopper Thomas Rogne.
Mowbray's defensive options have also been bolstered by Darren O'Dea's return from a loan spell with Reading.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.