(Recasts first paragraph, adds comments, update yield levels)

TOKYO, June 5 (Reuters) - Japan's 30-year government

bond prices rose after the weakest auction of the securities in

more than a year added to pressure on the Ministry of Finance to

reduce supply of super-long notes.

The bid-to-cover ratio, a measure of demand that gauges the

number of bids against the amount of securities on offer, fell

to 2.921, the worst since December 2023, and was down from 3.074

at the prior sale in May.

The auction followed a weak outcome of the 40-year bond sale

last week, and was a gauge for demand in so-called super-long

bonds, whose yields hit record highs in May after heavy

sell-offs.

"Investors bought the bonds as they thought the 30-year

bonds had become cheap," said Miki Den, a senior Japan rate

strategist at SMBC Nikko Securities.

"But fundamentally, the sentiment was supported by the

expectations that the finance ministry may cut the issuance of

super-long bonds," he said.

The finance ministry could reduce the sale amounts as early

as July, after hearing opinions from primary dealers at a

meeting scheduled later this month, strategists said.

Expectations for the move rose after Reuters reported last

week the Ministry of Finance is considering reducing its sales

of super-long bonds.

The 30-year JGB yield trimmed losses soon

after the auction, but fell as much as 7 basis points to 2.875%.

It was last down 6 bps at 2.885%.

Bond yields move inversely to prices.

Keisuke Tsuruta, a senior fixed income strategist at

Mitsubishi UFJ Morgan Stanley Securities, said some investors

probably rushed to buy back the securities to cover their short

positions.

"They needed to do so before bond prices rise further," he

said.

Yields across tenors fell, with the 10-year JGB yield

slipping 4 bps to 1.46%.

The five-year yield fell 3.5 bps to 1.005%.

The 20-year JGB yield fell 7 bps to 2.355%.

(Reporting by Junko Fujita, Kevin Buckland and Rocky Swift;

Editing by Mrigank Dhaniwala)