Authorities feared that the casualty toll could still rise significantly.
Erdogan, who flew late Sunday from Istanbul to Van province, said that the hardest-hit community was Ercis, where at least 50 bodies were found among 80 collapsed buildings. The state hospital in the region reported 1,000 injured.
Mustafa Erdik, chief of the Turkish earthquake observatory, said that the revised magnitude was 7.2, down from an initial estimate of 7.3, the Anatolia news agency reported. The quake struck at 1:41 p.m. (6:41 a.m. EDT), with an epicenter about 12 miles northeast of the provincial capital Van.
The epicenter was under the town of Tabanli, near the border with Iran.
Shaking was felt in Armenia, where panicked residents of Yerevan fled their homes.
Aid offers began to pour in from abroad, including Germany, Israel and Russia, as well as NATO, of which Turkey is a member.
Turkish President Abdullah Gul told Israeli President Shimon Peres that Turkey would manage search-and-rescue operations itself "at this stage," Peres' office said.
In the city of Van, 10 buildings collapsed, including one seven-storey apartment block.
Across the region, residents were labouring with shovels, iron rods and their bare hands to dig out survivors. Power outages complicated rescue efforts overnight.
The government's crisis team said 500 aid workers and doctors were being flown to the area.
The Turkish Red Crescent began distributing tents, blankets and food in the region. Health Minister Recep Akdag said an air ambulance and several helicopters would be sent to the quake-hit area, according to the Anatolia news agency.