CABRAMATTA firefighters were called out to Yennora Distribution Centre on Thursday morning after reports of the cotton bales re-igniting.
About 24 crews were at the scene to fight the original blaze at 10pm last Tuesday.
Cabramatta station officer John Moore said about $1 million worth of damage was caused during the first incident.
Mr Moore said it was important to "keep an eye on the site for at least the next couple of days".
He said embers were the main cause of the fire re-igniting.
"These kind of fires are rare but once they start it's very dangerous because it's not as simple as putting out the fire," he said. "It's very hard to ascertain the depth of the smouldering fire."
Fairfield station officer Grant Rice, who was one of the first to arrive at the scene on Tuesday night, said about 1000 bales were damaged.
He told the Champion on Monday that the site was safe.