Celtic make official Stuart Armstrong approach?

Celtic have reportedly made an official approach for Dundee United midfielder Stuart Armstrong.

The 22-year-old has 18 months remaining on his current deal at Tannadice Park.

Talks regarding a fee are ongoing between both clubs, according to Sky Sports News.

The former Scotland Under-21 international joined Dundee United from Inverness Caledonian Thistle back in 2009.

Armstrong's teammate Gary Mackay-Steven recently signed a pre-contract agreement with Scottish champions Celtic.