"Here, before this memorial, I am torn with feelings of unease because I survived, and by sadness in the face of the pain of the families," said Henri Zadjenwergier, 83, at the unveiling of a monument in the Baltic state'scapital Tallinn.
"As long as I have breath left in my body, I will bear witness to the fate of those innocent victims whose only 'crime' was to be Jews," he said.
Zadjenwergier is the only remaining survivor of Convoy 73, a train that left German-occupied France in May 1944 carrying 878 Jews.
It was one of 79 trains sent eastwards from a camp at Drancy near Paris.
While most went to German-occupied Poland, location of the Auschwitz-Birkenau death camp, Convoy 73 was the only one to travel to the Baltic. Historians been unable to establish why.
Some 600 victims were disembarked in Lithuania and killed.
The rest, including Zadjenwergier, were sent on to Estonia as forced labourers.
In September 1944, as Soviet troops rolled back the Germans, the 34 survivors were sent to a Nazi camp at Stutthof, now in Poland. Only 22 lived to return home when World War II ended in 1945.
Estonia was a battleground between Germany and the Soviet Union.
In 1941, German forces drove out the Soviets, who had seized the country the previous year under a pact with the Nazis. The Soviet Union deported thousands of Estonians to their deaths and were to do so again after the war.
The Nazis brought their own terror.
Estonia's pre-war Jewish population was some 4,400. Most fled before the Nazi invasion, but 1,000 died.
The Nazis sent around 10,000 Jews from other occupied countries to camps in Estonia.
"People became just numbers during the war and the total number of victims was only known to the planners and implementers of these crimes," Estonian Foreign Minister Urmas Paet told AFP at the ceremony.
"We must do our best to increase people's awareness of what happened," he added.
The Soviets drove the Nazis from Estonia in late 1944. The country was a Soviet republic until the communist bloc collapsed in 1991.