UPDATE 1-Brazil's Treasury foresees external issuances of $50 billion over next 10-15 years

(Adds further comments from secretary in paragraphs 3-9)

BRASILIA, May 14 (Reuters) - Brazil's government foresees external sovereign issuances of $50 billion over the next 10 to 15 years, Treasury Secretary Rogerio Ceron said on Tuesday during a Senate hearing.

In March, the government requested greenlight from senators to increase the limit of sovereign securities issued abroad from $75 billion to $125 billion, citing the need to tweak this ceiling as $74.3 billion has already been raised from 2004 to date, nearly exhausting the previously authorized cap.

The new volume requested by the government does not aim to increase public debt, as it represents the amount of maturities that will occur in the next ten years, said Ceron.

The Treasury aims to reissue these external bonds to keep the market liquid and provide corporations with a benchmark curve for private issuances, he added.

Opposition Senator Rogerio Marinho said during the hearing that he would propose an amendment to restrict this increase to $15 billion to be used until it is exhausted, so that the Senate can re-examine the issue in about three years.

In his speech, Ceron also mentioned that the dynamics of public debt depend heavily on the Selic basic interest rate, which guides short-term debt, representing 40% of the total.

"Every percentage point of the Selic has a brutal impact on the cost of public debt, this is very relevant," he said.

In a split decision last week, the central bank cut interest rates by 25 basis points to 10.50%, following six consecutive cuts twice that size.

All four board members appointed by leftist President Luiz Inacio Lula da Silva voted for a larger 50-basis-point reduction, arguing that there would be a reputation cost in not following a previously given guidance on that pace,

the minutes of the policy meeting

showed on Tuesday. (Reporting by Marcela Ayres; editing by Gabriel Araujo)