South Wales Fire Service has closed the only road going through a village near Blackwood while firefighters tackle a large fire.
The fire service has deployed appliances to a mountain near Wattsville, where 140 hectares of trees and bracken are alight.
UPDATE:Wattsville Mtn-140 hectares of trees and bracken well alight-6 crews dealing with incident. LKE #SWControl
South Wales Fire Service says it has dealt with more than 700 grass fires since the beginning of April, the majority of which were deliberately started.
Four youths aged between 12 and 14 were arrested in Maerdy on Sunday evening and have since been bailed pending further enquiries.
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Rain clipping the far north through the evening but elsewhere staying dry with some sunny spells.
Public Health Wales figures show 25 more cases of the virus have also been confirmed.
Photos taken on Saturday morning show Roald Dahl Plass strewn with empty beer bottles and discarded canisters of laughing gas.