The scale of the disaster was still emerging as rescue operations in the devastated zone northeast of the city of Tabriz pushed through the night after Saturday's quakes.
With telephone communications interrupted by the quakes, emergency teams were relying on radios and travelling in person to hard-hit villages to assess and rescue.
The quakes, which struck Saturday within 11 minutes of each other, measured 6.2 and 6.0 on the moment magnitude scale, according to Tehran University's Seismological Centre.
The US Geological Survey, which monitors seismic activity worldwide, ranked them as more powerful than that, at 6.4 and 6.3, respectively.
"Unfortunately, the toll is mounting and we are now at 180 dead and some 1,300 injured," Khalil Saie, the head of the regional natural disasters centre, told state television .
"Up to now, there are no deaths reported in the cities and all the victims come from rural areas," he said.
Earlier he told the television: "We are asking people to not panic. Help is arriving and rescuers are already at the scene."
President Mahmoud Ahmadinejad's office posted a statement on its website expressing condolences to those in the disaster zone and calling on authorities to "mobilise all efforts to help the affected populations."
According to the local Red Crescent, cited by the official news agency IRNA, at least 210 people had already been rescued and taken to hospital.
An emergency services official said 66 rescue teams were at work, using 40 devices and seven dog squads to detect buried survivors. He said 185 ambulances had been sent to the area.
Those hurt were taken to hospitals in Tabriz and Ardebil, the two biggest nearby cities, both of which escaped relatively unscathed by the temblors.
Villages outlying the towns of Ahar and Varzaqan, 60 kilometres (40 miles) from Tabriz, were decimated, being closest to the epicentres of the two quakes. Dwellings close to Heris, another town close by, were also badly shaken.
Residents in the region were terrified as their homes shook around them when the quakes hit, and they fled into the streets for safety, according to reports.
Tehran University's Seismological Centre said the first earthquake occurred at 4:53 pm (1223 GMT) with an epicentre just 60 kilometres (40 miles) from Tabriz, close to Ahar, and at a depth of 10 kilometres.
The second -- actually a big aftershock -- rumbled through from nearly the same spot. A series of more than 17 smaller aftershocks rating 4.7 or less rapidly followed.
The disaster zone was located around 90 kilometres from the borders with Armenia and Azerbaijan, and around 190 kilometres from the border with Turkey.
Iran sits astride several major fault lines and is prone to frequent earthquakes, some of which have been devastating.
The deadliest was a 6.6-magnitude quake which struck the southern city of Bam in December 2003, killing 31,000 people -- about a quarter of the population -- and destroying the city's ancient mud-built citadel.