Vietnamese soldier and journalist who fought against France and the US before becoming a critic of the communist government

Bui Tin, who has died aged 90, fought against French and US forces before turning into a thorn in the side of the Vietnamese government. Usually described as a war hero, he was a participant in key episodes of Vietnam’s wars as a soldier, journalist and official historian who was familiar with his country’s leading figures.

His first brush with history came in 1954 at the siege of Dien Bien Phu, where – as a political officer – he was wounded in the battle that ended French colonial rule. He next spent several years in Vinh, in northern central Vietnam, training officers and soldiers to be infiltrated into the south in anticipation of conflict with President Ngo Dinh Diem, seen by the US as a bulwark against communism in south-east Asia.

Infiltration was done through the Ho Chi Minh trail, which ran through Laos and Cambodia. Tin, who made two gruelling trips down the trail himself, later said that had President Lyndon Johnson agreed to General William Westmoreland’s request to penetrate Laos to cut the network of roads, the north could not have won the war.

He was sent to the south to report on the 1972 offensive and again the following year as the spokesman for North Vietnam’s military delegation at the four-party commission to implement the Paris agreement on the US withdrawal. Journalists described him as amiable, chatty and so willing to answer questions that he was mobbed by reporters when he appeared in public.

In the high point of an already eventful life, Tin, as a military reporter, was with the first troops who stormed the presidential palace in Saigon on 30 April 1975. President Duong Van Minh, South Vietnam’s last leader, offered a formal surrender to Tin, the most senior North Vietnamese officer on the scene. This led to accounts that Tin was the man who accepted South Vietnam’s surrender. However, Tin later said he had told Minh that there was no surrender to accept. “You don’t have any government to hand over to us,” he told Minh.

In another rendezvous with history, in 1979 Tin was among the vanguard of Vietnamese troops to enter the Cambodian capital of Phnom Penh, ending years of genocidal rule by the Khmer Rouge.

But after the euphoria of victory in Vietnam came disenchantment with communist rule. The revolutionary turned renegade in 1990. Having been invited to France by L’Humanité, the French communist newspaper, for its annual conference, Tin decided to stay. Instead of settling for a quiet life of exile, he turned into a vocal gadfly.

After only a few months in Paris, Tin rounded on his former comrades in a series of interviews with the Vietnamese section of the BBC World Service, which sent a journalist out especially to record him. Giang Nguyen, news editor for the Vietnamese service, said the broadcasts were so popular that the streets in Hanoi and Ho Chi Minh City, formerly Saigon, became virtually empty as people clustered their shortwave radios.

Tin questioned the party’s right to govern, its rigid ideology, accused it of corruption and blamed it for the country’s decline over the 20 years following reunification. He was not the first to call for economic and political reforms. Other figures, including General Tran Van Tra, had made similar noises in the late 1980s. But the timing of Tin’s broadcasts was felt particularly keenly by Hanoi, already rattled by events in the Soviet Union, where Mikhail Gorbachev was struggling to keep break-up at bay. Tin was denounced as a traitor by the newspaper Nhan Dan – the “voice of the party, state and people” – where he was once editor.

Born in Ha Dong, near Hanoi, Tin was born into a family connected with the imperial court in Hue, where his father, Bui Bang Doan, was a mandarin and lawyer. However, he spurned a life of privilege to join the anti-French resistance led by Ho Chi Minh when he was 18.

His criticism of Hanoi, ironically, came after the government had already embarked on economic liberalisation in 1986, a policy that paved the way for Vietnam’s current economic success. Nevertheless, Tin continued to air dirty laundry from the past. In his book Following Ho Chi Minh: Memoirs of a North Vietnamese Colonel (1995), he laid the blame for the disastrous land reform of the 50s, in which at least 10,000 “landlords” were killed, on Ho Chi Minh’s failure to stand up to his misguided Chinese advisers.

Tin was particularly critical of party figures such as Le Duan and Le Duc Tho – joint winner with Henry Kissinger of the Nobel peace prize. But Tin’s enduring support for the military campaign against the south and his admiration for General Vo Nguyen Giap, the military mastermind behind victory over the French and the Americans, and other top leaders such as Pham Van Dong and Truong Chinh, earned him the suspicion of other strongly anti-communist Vietnamese exiles.

Still, talking to the BBC as recently as June, Tin called on all Vietnamese to come together despite their political differences to help continue to rebuild a country torn apart by war.

One of 10 siblings, he is survived by two children – a daughter in Hanoi and a son in Canada.

• Bui Tin, soldier and journalist, born 29 December 1927; died 11 August 2018

• This article was amended on 27 August 2018 to correct the name of Tin’s father.