Uncertainty surrounding the durability of Michael Clarke's back and the suspension handed out to David Warner have forced Australia's selectors to add Steve Smith to the Ashes tour party until at least the start of the second Investec Test at Lord's.

Fawad Ahmed, meanwhile, will return home to Australia to complete his application for citizenship, though the national selector John Inverarity was at pains to stress that the legspinner may yet still be called into the Ashes squad at a later date. The 19-year-old left-arm spinner Ashton Agar is being kept with the squad as an intern, much as he had been in India earlier this year.

Smith made a century in difficult circumstances for Australia A against Ireland and then led the tourists to their narrow victory over Gloucestershire. Following the match he was informed of his inclusion for the next three weeks of the tour and possibly longer, given the currently parlous state of Australia's batting.

Widely considered unlucky to miss out on the initial squad of 16 following staunch performances in the final two Tests of the India tour, Smith is considered a future leader by the national selector John Inverarity.

"The first uncertainty was with David Warner's suspension. He won't be able to play before the first Test so his preparation will be anything but ideal," Inverarity said. "Even though Michael Clarke, his back is improving and we fully expect him to play in Taunton, there's that little bit of uncertainty about his back. So it could be that if Michael's back went again we'd be short of a batsman. So it was obvious we needed to bring another batsman in.

"Steve's a young man, we're really hoping he comes through as a player, he's a very talented player, good cricket sense, a good batter, runs between the wickets well, a brilliant fielder, his occasional leg breaks might come in handy, but he was the next batter and we needed the cover, it was very obvious. In Ireland it was apparently a very difficult wicket, some good players got knocked over early so he had to fight to get through it, and he did so very well, made a very good head-down hundred."

Ahmed found life difficult against Ireland and also Gloucestershire, but Inverarity said his most striking impression over the previous three days had been how difficult it was to bowl spin in cold weather and gusty winds at the County Ground in Bristol. Allowing for that difficulty, Ahmed showed glimpses of the quality that has seen Federal Government legislation changed to expedite his receipt of an Australian passport.

Though Agar is staying in England and Ahmed leaving, both are still part of the Australia A squad due to tour South Africa from mid-July, and Inverarity said his panel were still leaving themselves open to the possibility of adding one or the other to the Ashes squad should conditions dictate. The first two Tests of the series at Trent Bridge and Lord's may offer more to pacemen than spinners, with more helpful surfaces likely at Old Trafford and The Oval in the third and fifth Tests.

"I've said all along if we were to add a player to the squad it was likely to be a spinner - because of the Warner and Clarke situation we've actually added a batsman," Inverarity said. "But we still have that option open to add a spinner. Nothing's changed in that regard. Fawad's flying home tomorrow, and the procedure for him to become a citizen will continue, and then the intention is for him to go to South Africa, as it is for Ashton.

"Ashton being 19 years of age and being here it's an ideal development opportunity so he'll stay with the squad until he goes to South Africa. If we decide to have another spinner it will be one of those two. Ashton staying as a development player is no indication whatsoever that he's now ahead of Ahmed.

"My overwhelming impression [in Bristol] was that the conditions were terrible to bowl spin bowling. It was cold and with a gusty breeze. Very difficult conditions for him to bowl both in Ireland and here. He's a very good bowler. If we were to call on him he's broken the ice with the players and gets on very well with the players. He's a lovely man."