Japan's Prime Minister Shinzo Abe, whose first term in office ended in part for health reasons, sparked fresh speculation Monday about his well-being with an unexpected, hours-long hospital visit.

Abe emerged from the Tokyo hospital where he was previously treated for ulcerative colitis more than seven hours after he entered, and left by car without saying anything, according to TV footage of local media.

His previously unannounced arrival on Monday morning prompted a local media frenzy and comes after weeks of speculation about his health.

A weekly magazine report in July claimed Abe had been vomiting blood, but government spokesman Yoshihide Suga insisted the prime minister was healthy.

More recently, questions have been raised about the prime minister's decision to avoid holding any press conferences, despite rising criticism over the government's handling of the coronavirus outbreak domestically, where infections are increasing.

Analysts have suggested the prime minister has struggled to answer questions in public appearances, and one television even analysed the speed with which Abe walked a route in the prime minister's office, concluding he was moving slower of late.

Local media said Monday that Abe completed his regular annual health check-up in June but cited an aide as saying he was now undergoing an additional "one-day regular health check-up".

Shinzo Abe is Japan's longest-serving prime minister
Shinzo Abe is Japan's longest-serving prime minister POOL / Rodrigo REYES MARIN

Over the weekend, a senior member of Abe's Liberal Democratic Party appeared to suggest the prime minister needed to take a break.

"We need to force him to get rest, even just for a few days," Akira Amari told a local television station.

Abe is now Japan's longest-serving prime minister, but his first term ended abruptly with his resignation just one year into office in 2007, when he cited his health among other factors.

His illness came after a series of scandals surrounding his government that drove down his approval ratings and resulted in a massive election loss.

Abe was diagnosed with ulcerative colitis, but upon returning to power in 2012 said he had overcome the condition with new medication.

While Japan has seen a comparatively small coronavirus outbreak compared to the world's worst-hit countries, Abe has been criticised for several policy flubs in handling the crisis.

His programme to distribute cloth masks to each household was widely mocked, and he was forced into an embarrassing U-turn on distribution of stimulus funds.

His approval ratings have sunk during the crisis, though the country's divided opposition have regularly failed to capitalise on falls in Abe's ratings.