SREI SNAM, Cambodia — Fighting between Thailand and Cambodia spread on Tuesday to new parts of their contested border as the toll rose to 10 killed and more than 140,000 civilians fled the violence.

The two countries have blamed each other for the renewed clashes over their century-old border dispute, which saw Thailand launch airstrikes and use tanks against its neighbor on Monday.

Cambodia's Senate President Hun Sen said his country had retaliated against Thailand, after Phnom Penh denied firing back for two days.

Tens of thousands of people have evacuated from border regions since the fresh fighting began on Sunday, officials said.

Cambodian Poan Hay, 55, said she left her home in Oddar Meanchey Province on Monday as soon as she heard gunfire — the fourth time she evacuated this year because of on-and-off fighting on the frontier.

"I am so angry at the Thai army, but I ask them to stop firing at Cambodians," Poan Hay told Agence France-Presse.

She is sheltering at a pagoda with relatives about 70 kilometers from the border in Siem Reap Province's Srei Snam.

Cambodia accused Thai forces of shelling positions overnight, which killed two people traveling on a national road.

Seven Cambodian civilians have been killed in total and about 20 wounded this week, the interior ministry said. More than 21,000 people have been displaced from three border provinces, it said.

The defense ministry said the Thai army had resumed attacks around 5 am on Tuesday in the border regions, including in the area of centuries-old temples, such as the UNESCO World Heritage Site, the Preah Vihear temple.

The Thai army said three soldiers have been killed since Monday.

One was killed on Tuesday by indirect fire in Surin Province while a grenade killed another soldier in the area of the Preah Vihear temple.

Nearly 500 temporary shelters have been established across several border provinces, housing more than 125,000 civilian evacuees, the government said.

Thai navy spokesman Parat Rattanachaiphan said in a news conference that Thai forces recently detected Cambodian troops, settlements and several weapon bases in a disputed coastal area of Trat Province.

Parat accused Cambodia of escalating tensions by deploying unmanned drones to provoke Thai forces.

Early on Tuesday, he said Thai forces "launched a military operation to drive them out".

In Surin Province, Sutida Pusa, 30, who runs a small food shop, told AFP on Monday that her young and elderly relatives were moved to an evacuation center the day before, while others stayed behind to guard their property.

She has traveled back and forth between the temporary shelter and her house — located less than 20 kilometers from the border — to care for family members in both places.

"I wanted to see the situation first, as the sounds of fighting aren't as loud as during the major clash on July 24," she said.

Agencies Via Xinhua