RIYADH, Feb 19 (Reuters) - Saudi Aramco is likely to issue a bond this year and will prioritise longer maturities of up to 50 years, Chief Financial Officer Ziad Al-Murshed said on Monday.

The planned issuance is part of a strategy to optimise the company's capital structure, Al-Murshed told an audience at the Saudi Capital Markets Forum in Riyadh.

Aramco last tapped global debt markets in 2021, when it raised $6 billion from the sale of a three-tranche sukuk, or Islamic bond.

Gulf companies and governments have rushed to tap debt markets since the start of the year to take advantage of recent falls in global interest rates, with oil-rich Saudi Arabia issuing $12 billion of dollar-denominated bonds in January.

"There was a period of inactivity because the markets were not stable. Now, the markets are becoming more stable so you can expect us to be more active," Al-Murshed said.

The Saudi energy ministry last month ordered Aramco to halt plans to boost its maximum sustainable capacity to 13 million barrels per day (bpd), returning to the previous 12 million bpd target.

The company is due to announce annual financial results and dividend payments in March. Last year, it introduced a special, performance-based dividend.

The Saudi state is Aramco's biggest shareholder by a large margin and relies heavily on its generous payouts.

Still, it is poised to sell more Aramco shares, three people familiar with the matter told Reuters earlier this month, which could boost the country's funding and its aim of shifting the economy away from oil.

Asked about such reports, Al-Murshed said he could not comment as it was not the company's "decision as to the sale of existing government shares".

The share sale could raise about $20 billion, according to Bloomberg. Saudi Aramco has not confirmed the figure.

Aramco completed the world’s largest initial public offering in late 2019, raising $25.6 billion and later selling more shares to raise the total to $29.4 billion. (Reporting by Alexander Cornwell and Pesha Magid; editing by Barbara Lewis, Kirsten Donovan)