An Alabama army veteran who was captured in Ukraine while voluntarily helping the country fight Russian invaders spoke with his mother on Tuesday and said his captors were “anxious to begin negotiations for his release”, according to his family.

Alex Drueke did not communicate any demands from his captors or say when negotiations should start during the 10-minute conversation with his mom, said Lois “Bunny” Drueke, in a statement Wednesday from her and his aunt, Dianna Shaw.

But Drueke’s mention of possible negotiations for his release came after the leader of the Russian-controlled territory Donetsk in Ukraine – where he is being detained – said he did not plan to swap him or another captured Alabama veteran for Russian prisoners of war.

Bunny Drueke on Wednesday also said that her son “sounded tired and stressed, and he was clearly reciting some things he had been made to practice or read, but it was wonderful to hear his voice and know he’s alive and all right”. She added that he described spending most of his time in captivity but has food, water and bedding, and he asked repeatedly about the well-being of his dog, a mastiff named Diesel.

Additionally, Alex Drueke, 40, said he had not spoken with his fellow Alabama prisoner in Donetsk, Andy Tai Ngoc Huynh. He presumed Huynh, 27, was being held in solitary confinement as well.

“I told him I was doing everything I knew to do to help get him and Andy released,” Bunny Drueke added.

Alex Drueke completed two tours of combat with the US army in Iraq – leaving him with post-traumatic stress disorder – before arriving in Ukraine via Poland in April, according to his mother. He was teaching Ukrainian soldiers how to use weapons they received from other countries in their fight against Russia’s invasion, which began in February.

Tuesday’s talk was the first communication between mother and son since 8 June, when he texted her and told her he would be out of reach for the next few days. A member of Drueke’s unit later called his mother and told her that he and Huynh had been captured by Russian forces during a battle on 9 June north of Kharkiv, Ukraine’s second-largest city.

He and Huynh, who previously served with the US marines, were taken to a detention center in Donetsk, where Russia’s moratorium on the death penalty is not in effect. The Kremlin has claimed both men face execution, after a court in Donetsk gave death sentences to two Britons and a Moroccan national caught fighting for Ukraine.

Drueke spoke with the US state department before the follow-up conversation with his mom.

A Russian state news agency on Wednesday released an interview showing Drueke recounting how his only combat experience in Ukraine occurred on the day of his capture.

“I didn’t fire a shot,” Drueke said, according to the news agency Reuters, who described his words as an apparent plea for leniency. “I would hope that would play a factor in whatever sentence I do or don’t receive.”

Ukraine’s president, Volodymyr Zelenskiy, has said his government would do what it could to ensure the safe return of Drueke and Huynh, labeling the American pair “heroes” for volunteering to help his nation fight Russia.

“We are grateful the Ukrainian government is standing behind Alex and Andy,” Shaw’s statement Wednesday said.