ATHENS, June 2 (Xinhua) -- Greek conservatives of main opposition New Democracy (ND) party won the second round of local elections on Sunday, which had turned into a crucial test for all parties ahead of the early national polls which will most likely be held on July 7.

ND backed candidates won 12 out of 13 regions across Greece and the overwhelming majority of the 332 municipalities, according to the official results released by the Interior ministry, with 75 percent and 62 percent of votes counted respectively.

ND had won a strong lead in the first round on May 26 which coincided with the European Parliament elections.

Following the conservatives' victory also in the European battle with 33.1 percent of votes against 24 percent for the ruling Radical Left SYRIZA party, Greek Prime Minister Alexis Tsipras has decided to proceed to snap national polls.

After the second round of local elections, he will visit Greek President Prokopis Pavlopoulos to initiate the procedures for early elections, Tsipras said on the night of May 26.

The general elections will most likely be held on July 7, the government said last week.

An opinion survey released on Sunday evening showed that SYRIZA was trailing ND in the battle for the national elections as well.

Should ballots for general elections were held this Sunday, the conservatives would win with 31.5-36.5 percent of votes against 22.5-27.5 percent for SYRIZA, according to a survey conducted by polling firm Pulse for local SKAI television.

The centrist Movement for Change (Kinima Allagis- KINAL) would rank third with 6.5-9.5 percent of votes and the Greek Communist party KKE would follow with 4.5-6.5 percent.

The last two parties passing the three percent of votes threshold required to enter the next parliament would be the far-right Chryssi Avghi (Golden Dawn) and the right-wing nationalistic Elliniki Lysi (Greek Solution), receiving 4-6 percent and 3-5 percent respectively.

The survey was carried out in the period May 30-June 1 on a sample of 1,358 voters.

On Sunday evening Tsipras congratulated all new mayors and regional governors and sent the message that the war is not over.

"In life and politics it is important to know how to win, but also how to lose and stand on your feet to continue fighting," he told media on Syntagma square standing next to SYRIZA's candidates who lost the battles for the Regional Governor of Attica and the municipality of Athens.