Brentford: Jake Bidwell and David Button sold for economic reasons - Dean Smith

Jake Bidwell (left) and David Button departed Brentford this summer for QPR and Fulham respectively

Brentford head coach Dean Smith says "economic" reasons were behind the sales of Jake Bidwell and David Button to west London and Championship rivals.

Former Bees skipper Bidwell, 23, joined QPR earlier in July while goalkeeper Button, 27, moved to Fulham on Tuesday.

Both players would have been out of contract at Griffin Park in 2017.

"Economics tells you that if players don't want to commit then you try to get the best deal you can for them," Smith told BBC Radio London.

"We have done that with Bidwell and Button."

Left-back Bidwell and Button had been first-team regulars over the past three seasons for the Bees, with both players making more than 130 appearances since August 2013.

Smith says Button was offered a new contract last season but the former Tottenham trainee stalled on negotiations.

"We tried to get David to sign a new contract, and he was offered one before I came to the club," Smith added.

"I'd spoken to him a number of times about it and he wanted to wait until the end of the season.

"As is the nature of economics in football with someone going into the last season of their contract, however good they are, it means the club could end up with nothing at the end of it.

"David didn't want to commit himself and the club didn't want David running his contract down."