Four charged after $3.5m cannabis found

Four people have been charged after nearly $3.5 million worth of cannabis plants were seized from homes in Sydney's west.

Police raided properties in Greystanes, Guildford, Merrylands and Dundas on Friday.

Officers seized 686 cannabis plants with an estimated potential street value of $3,430,000 along with $222,600 in cannabis leaf.

About 5.40am police arrested three men aged 23, 25 and 36 as well as a 23-year-old woman.

They were charged with numerous offences including drug offences.

The three men were refused bail and are due to appear before Parramatta Local Court on Saturday.

The woman was refused bail and was due to appear before Parramatta Local Court on Friday.