MELBOURNE has secured the prized signatures of brothers Tom and Oscar McDonald, with the pair extending their time at the club until the end of 2018.

The key signings consolidate the Demons' backline for the next two seasons.

From Horsham in north-west Victoria, Tom joined Melbourne in the 2010 NAB AFL Draft at pick No.53 while the Demons used the exact same pick in the 2014 NAB AFL Draft to bring the younger brother Oscar into the club.

Tom played his 100th game this season while Oscar has developed ahead of schedule, playing 12 games in defence this season to build upon the two games he played in his first year.

Melbourne football manager Josh Mahoney said the club was rapt to secure an agreement with the key position pair.

"Both of these signings are very important components for the structure of our team in future years," he told melbournefc.com.au.   

"We have been negotiating throughout the year with [their manager] Alex McDonald to get both of these deals done and we’re very happy that we’ve been able to come to an agreement on Oscar and Tom."

The Demons have now locked in their key re-signings for 2016 and are understood to be in the market for Essendon's Michael Hibberd and have also been linked to Michael Hurley.

The club has won nine games in 2016 and has a percentage of more than 100 per cent heading into round 21.

Tom McDonald has since finished third in Melbourne’s best and fairest award on two occasions, in 2012 and 2015.

He also received a NAB AFL Rising Star nomination in 2012.

He said it was a relief to put pen to paper.

"It’s not something you stress about every day, but it does play on your mind a little bit," McDonald told melbournefc.com.au.

"It’s good to have it done – have a bit of continuity and commit for the future."