• Both players want to be rewarded for key role in club’s promotion • Manager Mark Warburton yet to also sign new deal at Ibrox

Rangers’ return to the Scottish Premiership could be hampered by the loss of two key players, after Martyn Waghorn and James Tavernier rejected new contracts from the Ibrox club.

English sides have now been alerted to the duo’s unhappiness over how negotiations have unfolded. Mark Warburton, the Rangers manager, is also still to sign a new deal, which has been under discussion since May.

Since the end of last season, Rangers have signed Joey Barton and Jordan Rossiter on what is believed to be vastly superior terms to Waghorn and Tavernier. The club captain Lee Wallace has also signed a new contract.

Offers made to Waghorn and Tavernier – they have existing deals until 2018 – were rejected around a month ago, with apparently no current scope for renegotiation. The pair are keen to stay in Glasgow and have relished their time there, but they also want to be rewarded for what they believe has been a key role in Rangers’ rejuvenation. Warburton’s own scenario also remains a point of intrigue, although the manager has swatted aside any suggestion that he could leave Scotland imminently.

Both Waghorn and Tavernier were star performers as Rangers cantered to the second-tier title last season and reached the Scottish Cup final. Waghorn, a former Sunderland and Wigan striker, scored 28 goals in all competitions despite suffering an injury in mid-February which left him out of action until May. The 24-year-old right back Tavernier played in every league game of the previous season, scoring 15 times in all competitions.