Japan's Prime Minister Shinzo Abe on Sunday visited a memorial to a Japanese diplomat who saved 6,000 European Jews from the Holocaust by issuing visas from war-torn Lithuania, in defiance of Tokyo.

Abe visited the two-storey building, now a museum, that housed the consulate where Chiune Sugihara worked in the Baltic state's second city Kaunas.

"The courageous humanitarian act of Mr Sugihara is highly appreciated by the whole world," Abe said, adding that the diplomat worked with "conviction and passion".

"I am really very proud of him as a Japanese."

Ahead of the visit on Saturday, he told reporters Sugihara's memory still provides guidance in a world "where rule of law and international order are being challenged in various forms".

The diplomat, who died in 1986 aged 86, is thought to have been among around 15 who issued visas for European Jews during World War II.

He is often called "Japan's Schindler" -- a reference to German industrialist Oskar Schindler who is credited with saving 1,200 Jews during the Holocaust.

"Sugihara needed a lot of courage to do what he has done, especially when we know that it was dangerous for him to defy the government's orders," the head of Lithuania's Jewish community, Faina Kukliansky, told AFP.

Lithuania's Foreign Minister Linas Linkevicius described the visit as "emotional".

- 18-hour days -

Sugihara was appointed vice-consul in October 1939, one month after German and allied Soviet forces attacked and carved up neighbouring Poland.

Japan saw still-independent and neutral Lithuania, which harboured thousands of Polish refugees, as a perfect location for the polyglot Sugihara to collect intelligence about military developments in the region.

But when Moscow invaded the country crowds of Jewish refugees, mostly from occupied Poland, started lining up at the Japanese consulate seeking visas to flee.

Sugihara wasted no time in issuing visas, sometimes working 18 hours a day and evading strict instructions issued by Tokyo.

With visas in hand, Jews took a gruelling two-week railway trip across Russia to Vladivostok in the far east and then travelled by boat to Japan.

Many of them were later sent to the Shanghai Ghetto and stayed there until the end of the war.

Sugihara received Israel's "Righteous Among the Nations" title honouring people who saved Jews during the Holocaust in 1984.

Abe, who has been criticised for appearing to minimise Japan's own atrocities during the war, is on a six-day trip in the Baltics which will also take in Bulgaria, Serbia and Romania.