Midfielder Newton and defender Dummett (pictured right) would see their contracts expire this summer, but the club have moved to secure their futures.
The pair enjoyed successful loan spells at SPL outfit St Mirren last season and helped the club to secure the League Cup, which was the club's first success in 26 years.
Dummett made 33 appearances for St Mirren after arriving on loan last summer, while Newton featured in 17 games following his arrival in the January transfer window.
Lee Clark wanted to take Dummett to Birmingham, and a loan deal could be sorted next month.
Motherwell (A) July 16
Rio Ave (A) July 20
Pacos Ferreira (A) July 23
Blackpool (A) July 29
St Mirren (A) July 31
Braga (H) August 10
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