Croatia has been sending the CL-415 canadair and Mi-8 MTV helicopter to Nova Gorica each day over the last four days, the Croatian Defence Ministry said on Saturday.
The request for assistance was forwarded to Croatia via the EU Civil Protection Mechanism.
In the night between Friday and Saturday, over 800 local firefighters were engaged on the ground.
Ten villages were evacuated due to thick smoke.
The disaster has taken one life so far. On Thursday evening, a 56-year-old Italian woman, who was a volunteer civil protection operative, was killed when a burned tree trunk fell on her while she was patrolling the area along the Italian-Slovenian border hit by that wildfire that erupted in the Kras region.
According to reports by Italian media outlets, the victim Elena Lo Duca was in teams that conducted on-site inspections of the scope of the damage at the affected area when the tree fell on her and killed her.
The wildfire has affected over 2,000 hectares of land.
Slovenian Civil Protection head Srečko Šestan said two days ago that this was the largest fire in the history of independent Slovenia.
Apart from Croatia also Italy, Austria and Slovakia have sent water-dropping planes to help local firefighting forces.
According to the estimates from Slovenia, the blaze could be put out next week when some rain is expected.