Jeffers has recently turned down a moves to Ipswich Town and Cardiff City as wages were a stumbling block although it is believed that Wednesday can match his personal terms.
The former Arsenal man made his name at Everton where his goal-scoring exploits got him a £7million move to Highbury but he failed to recapture his form and has since has spells at Charlton and Ipswich although is well down the pecking order at Ewood Park.
Jeffers has also played for England - scoring on his debut against Australia in 2003 - and is looking for a move to rekindle his once-prolific career.
Riordan meanwhile has been linked with Wednesday in the past while he was at Hibernian although chose to move to Parkhead although his first-team chances have been limited.
The Scot, capped only once by his country, scored 54 goals in five seasons for Hibs before a £200,000 move to Celtic but he has failed to hold down a first-team place.
It is rumoured that Wednesday will bid around £400,000 for the player who despite his limited opportunities in Glasgow, is very popular with the fans.