Both Abbott and Hardie are on the fringes of Australia's squad for the T20 World Cup, which clashes with the first month of Blast group games. Both players made appearances in their recent series win over West Indies, but neither features in Australia's full-strength squad for their upcoming three-match series in New Zealand, which starts in Wellington next week.

"Sean is a highly skilled cricketer, and everyone saw last season what he is capable of in red-ball and white-ball cricket," Alec Stewart, Surrey's director of cricket, said. "He had an outstanding impact as a cricketer and as a member of the dressing room Sean is exactly what we look for in an overseas professional at this club."

Their squad is certain to be affected by England's T20 World Cup plans, with Gus Atkinson, Sam Curran, Will Jacks and Reece Topley highly likely to be involved and Tom Curran, Chris Jordan and Jamie Overton also in contention.