ROME, Oct 20 (Reuters) - Italy will issue a new global dollar-denominated bond this year and is likely to focus the sale on one or two maturities, the Treasury's head of debt said on Tuesday.

"We are closing the authorisation process with the Securities Exchange Commission," Davide Iacovoni said, adding the issue would be "in coming weeks, by year-end at the latest".

Last year Italy, the world's third-largest public debtor, raised $7 billion with its first U.S. dollar bond in nearly a decade, diversifying its funding sources.

Rome is set to borrow some half a trillion euros this year, to help weather the pandemic and is aiming to gradually double the amount of Italian sovereign bonds held by small retails investors.

The Treasury, which manages a debt worth more than 2.4 trillion euros, is also finalising the framework for the next issues of a green bond, but has yet to decide whether these will happen this year or at the beginning of 2021.

The green bonds will be offered to institutional investors but Rome is considering opening them up to retail clients too.

The sale of the next BTP Futura - a debt instrument dedicated to retail investors only which was first launched this year - will take place between Nov. 9-13, Iacovoni said.

The bond will have an 8-year maturity and will pay the same premium as the latest issue, in July.

Issues in coming months will be down more than 30% compared to the same period last year as the Treasury can count on a liquidity of almost 84 billion euros at the end of September, almost double the 44.7 billion euros in the same period of 2019.

"This will allow us to reduce the amount of issues compared to what we did last year. The debt structure remains unvaried, and protects us from refinancing risks," Iacovoni said. (Reporting by Stefano Bernabei and Antonella Cinelli, writing by Agnieszka Flak and Giulia Segreti, Editing by Angus MacSwan)