Pompey have been linked with a move for highly-regarded Brighton keeper Christian Walton.
According to the Argus, the 21-year-old has been earmarked for a loan spell in a bid to earn more first-team experience.
That has brought him to the attention of Pompey, Wigan and Peterborough.
The Seagulls have this summer completed a club record deal for Australian international Maty Ryan, while number one Niki Maenpaa is expected to sign a new contract.
That leaves Walton in need of match action elsewhere as he enters the final 12-months of his existing deal.
Last term he made 31 appearances for Luton and had seven outings at Southend during loan spells.