Republic of Ireland Under-19 captain Rob Kiernan will join Scottish Premier League club Kilmarnock on loan until the end of the season subject to international clearance.

Kiernan has been on trial with the SPL side since last week and Jimmy Calderwood has moved to secure the centre back until the end of the season.

The 19-year-old, who made his one and only Watford appearance in the FA Cup last January, has also signed a contract extension until June 2011, after the Hornets took up their option of an extra year.