Madrid manager Carlo Ancelotti, mindful that he had angered Spurs boss Andre Villas-Boas with his previous comments about Bale, refused to discuss the club's mooted world-record move for the 24-year-old on Tuesday night.
But Casillas, who recently described Bale as one of the top three players in the world, did not toe the same line.
"We still don't know if it's official or not. There has been a lot of talk about it in the last few days, just like in every pre-season," the Real goalkeeper said in AS.
"Last year it was Modric and now it's 'the Bale saga'. The president (Florentino Perez) and (director general) Jose Angel Sanchez always do everything to try and bring the best players to the club.
"The current squad is complete in every area but if a player like Bale comes along, he'll be welcomed."
Casillas' comments will no doubt be received with disappointment at Spurs, who have been keen to keep talk of Bale's possible departure to the Spanish capital to a minimum.
Spurs sources tried to play down claims made in the Spanish media that Perez is due to meet Daniel Levy in Florida, although they did admit the Tottenham chairman is currently there on holiday.
Such has been the interest in Bale that photographers and camera crews turned up at the club's training ground on Tuesday to see if the Welshman would report for duty.
But despite the frenzied speculation engulfing White Hart Lane, former captain Ledley King is sure the players will be able to concentrate on starting the season with a bang.
"At this time of the season, you are not sure what's going to happen," King said at the launch of the club's new interactive online game Tottenham Turfies.
"I'm sure every club is the same. As players you learn to deal with that. "You just get your head down and concentrate on performing your best for the team and that's what the players will be doing."