Pat Murphy reports (BBC Radio 5 Live)

Giles, who plays county cricket for Warwickshire, was summoned from Brisbane where he was staying with the team for the triangular one-day tournament which follows the Test series.

He increases England's bowling options for the fifth Test, which starts in Sydney on Saturday.

"If he does play, it will be asking a lot, but we feel this fellow is up to it. He has played big games for Warwickshire, he's already played one Test match and we fell, if he is asked, there won't be a problem," said England captain Alec Stewart.

"The SCG has a history of turning and Ashley gives us another option," Stewart added.

Australia expect spin to be an important factor in the outcome of the match and have included two leg-spinners, Shane Warne and Stuart MacGill, and off-spinner Colin Miller in their squad.

"Everyone will be nervous - it's a big test for England. Everyone is going to have a few butterflies but you have got to try and control that and get on with the job," Giles commented.

England have released seam bowlers Angus Fraser and Dominic Cork from the squad, so they can play in a one-day game against a Bradman XI at Bowral on Friday.

Switch transformed career

Giles was born in Surrey and began his cricket career with his home county as a seam bowler.

Giles in one-day action for England

He switched to spin when he moved to Warwickshire four years ago and quickly developed into a bowler of international potential.

He bowled well at Sydney on the England A tour in 1996 and finally made his Test debut against South Africa at Manchester last summer.

Giles, now 25, achieved modest figures of one for 106 in a South African total of 552 for five declared.

He did not figure in the rest of the series but was included in the squad for the Wills International Cup one-day tournament in Dhaka, which took place in October.

Teams for the fifth Ashes Test:

Australia (from): Mark Taylor (capt), Michael Slater, Justin Langer, Mark Waugh, Steve Waugh, Darren Lehmann, Ian Healy (wkt), Shane Warne, Stuart MacGill, Damien Fleming, Colin Miller, Glenn McGrath.