After spending several days in a basement in fear of Russian bombs in southern Ukraine, 15-year-old Arsen and his mother Irina reached Moldova. But the teenager is already longing to return home.

Arsen described the terror the family felt "holed up in the basement of a building" for three or four days before deciding to leave.

"This nightmare must end," said Irina, tears in her eyes and trembling under the icy wind sweeping the Palanca border post in eastern Moldova.

But more than the cold, it was the fear that tormented her.

"The situation in Ukraine is deteriorating," the teacher told AFP, hugging her two small dogs wrapped in blankets. "That's why I had to make this difficult decision and leave."

Packing in a rush with only some documents and clothes for her two teenage sons, Irina left her mother behind as she did not want to leave the Black Sea port city of Odessa, some 40 kilometres (25 miles) from Palanca.

Even in Palanca, the sound of planes flying near the border could be heard throughout the night. The flow of refugees shows no sign of letting up.

Since the invasion began last week Moldova, a former Soviet republic landlocked between Romania and Ukraine, has seen nearly 80,000 refugees arrive according to figures from the UN refugee agency.

Nearly 875,000 people have fled Ukraine in total, the UNHCR said Wednesday, and the number are expected to rise.

"I have spoken Russian since my childhood, but I am Ukrainian," said Irina. Russian President Vladimir Putin she described as "a monster".

"He says he wants to help the Ukrainians, but I don't need his help," said the 40-year-old, who declined to give her surname.

On the narrow road leading to the border post, a huge traffic jam formed late Tuesday with cars to pick up refugees coming and going.

Hundreds of refugees, mostly with children, hugged and comforted each other there, as volunteers distributed tea, coffee and snacks.

"Your brother will come, you'll see," Lioudmila, in her 50s, reassured a friend who found herself alone at the post with her four-year-old son in her arms.

Like Lioudmila, many refugees needed transport to reach Moldova's capital Chisinau or neighbouring Romania, squeezing into cars with volunteers or relatives between strollers, suitcases and other bundles of hastily packed belongings.

Others walked under the falling snow the five kilometres separating the border post from a camp of tents, which the Moldovan authorities erected on the muddy grounds of a village stadium.

Another of those who fled was 17-year-old Alexei who echoed the thoughts of many Ukrainians before boarding a bus to take him to Chisinau.

"We want to live in our country, free, without the Russian army."

Moldova is among the poorest countries in Europe with some 2.6 million inhabitants.

Moldovan President Maia Sandu was elected in 2020 on a pro-Western platform, and the country is embroiled in a dispute with Russian gas giant Gazprom over outstanding payments.