Spain plans to issue a 10-year syndicated bond this month, a Treasury official told Thomson Reuters service IFR on Tuesday, replicating last year's issuance pattern as jittery markets push its yield spreads near euro-era highs.

If market conditions allow we are planning a 10-year syndicated deal later this month, although no mandate has been given yet to any group primary dealers, public debt manager at the Spanish Treasury Ignacio Fernandez-Palomero Morales told the news and analysis service.

It remains part of the natural syndication process as the current 10-year issue will reach in the near term its maximum targeted size and we traditionally sell a new 10-year in January, he said.

The Spanish Treasury regularly syndicates new benchmarks of 10-, 15- and 30-year bonds whenever it considers that the current maturities have reached targeted liquidity levels, the official noted.

Last year Spain's Treasury syndicated a 10-year transaction in January and a 15-year in February.

A report in newspaper El Mundo said Spain was lining up a 10-year syndicated 6 billion euro ($7.77 billion) bond this week, but the Treasury said there was no visibility on the issue's size.

Spain's debt market is under intense scrutiny as funding costs rise on the back of mounting investor concerns focused on the euro zone's periphery and a possible bailout plea by Portugal.

The premium investors demand to hold Spanish debt over equivalent German Bunds rose to 278 basis points on Tuesday, close to the just over 300 bps euro-lifetime high hit in December.

The Treasury is expected to pay high yields on a 5-year bond issue on Thursday in what will be its first auction of the year.

(Reporting by Michael Winfield; Writing by Paul Day; Editing by John Stonestreet)