Sandaza, 27, who is out of contract at the end of the season, has scored 13 goals in 18 games since moving north from Brighton in the summer on a one-year deal.
Rangers are keen on the Spaniard but Brown dismissed reports the Ibrox side had tied-up a lucrative pre-contract agreement with the player.
Brown said: “It’s my understanding Rangers have spoken to Fran but there’s no agreement at present. They are well within their rights [to speak to him] and I have no problem with that.
“We have parties interested in Fran in Scotland and England but there have been no concrete offers from Rangers or anyone else.
“We have offered Fran probably the best deal of any Saints player in recent times but we certainly couldn’t compete with offers of £5,000 a week or more.
“We don’t want to lose him before May. We have targeted a top six place. There are no guarantees in football but his goals could be the difference between the top and bottom six. That would be the starting point for any bid.”
One deal that is almost complete is the transfer of Dundee United’s talented midfielder Scott Allan to West Bromwich Albion. The clubs have agreed a fee which is believed to be in the region of £400,000 and the player has passed a medical at the Hawthorns.
Roy Hodgson, the West Brom, manager, said he would have no hesitation in throwing Allan into his side immediately. “Yeah, why not?” Hodgson said. “He’s played in the Scottish Premier League. He is one of the most exciting talents in Scottish football. He’ll be moving from his comfort zone in Scotland to readjust to life in Birmingham. Certainly, he’ll come into the first-team squad straight away and we’ll see what impact he can make.”
Allan, 20, rejected a new contract offer from Dundee United in September, infuriating manager Peter Houston who accused him of being motivated only by money. Houston also claimed the player had been badly advised by his agent, John Viola, who denied Allan was greedy.