UPDATE: A GRASSFIRE that burnt through 10ha of land and threatened homes in Pakenham is being treated as suspicious, police say.

The CFA issued an emergency warning for Pakenham and Pakenham Upper as the blaze put homes in the area under direct threat yesterday afternoon.

Residents near Army Road and Reynolds Road were told to implement their fire plans before the blaze was contained later yesterday.

Police say they are investigating the blaze and are treating it as suspicious.