(Rewrites first paragraph with bond sale, adds details and background throughout)

DUBAI, July 10 (Reuters) - Saudi Aramco has begun a three-part bond sale, news service IFR reported on Wednesday, which could raise at least $3 billion, a source with knowledge of the matter previously told Reuters.

The sale comes after Saudi Arabia raised a total of $12.35 billion from a much-anticipated secondary share sale in Aramco, after increasing the size of the offering, a document showed.

The bond sale marked Aramco's return to debt markets after a three-year hiatus, taking advantage of favourable market conditions.

Aramco has long been a cash cow for Saudi Arabia, which is seeking funds to invest in new industries and wean its economy away from oil under its Vision 2030 plan.

The oil giant expects to pay out $124.3 billion in dividends for 2024, the majority of which goes to the government, which directly owns about 81.5% of the company.

With the latest bond sale Aramco joined top firms and governments in the Gulf rushing to markets this year to fund investments. The proceeds will be used for general corporate purposes, IFR reported.

Under the three-part bond sale on Wednesday, Aramco is selling bonds maturing in 10, 30 and 40 years. It gave an initial guidance around 140 basis points (bps) over U.S. Treasuries (UST) for the 10-year bond, 180 bps over UST for the 30-year, and 195 bps for the 40-year, IFR reported.

State-owned companies in emerging markets issued dollar-denominated bonds worth $21.4 billion in the first half of the year - up 22% from a year earlier, according to a report by investment firm Tellimer.

Saudi state-owned firms led the group with 23% of the overall issuance value, while the government raised $12 billion of dollar-denominated bonds in January and $5 billion in sukuk, or Islamic bonds, in May.

Aramco last month was awarded $25 billion worth of contracts for its gas expansion plans. It also said it would buy 10% of Renault and Geely's thermal engines joint venture Horse Powertrain, and announced a non-binding deal with U.S. energy firm Sempra to buy liquefied natural gas.

Aramco last tapped global debt markets in 2021 when it raised $6 billion from three-tranche sukuk. It flagged in February it was likely to issue bonds this year.

Its 40-year tranche would become its second-longest dated bonds after $2.25 billion of notes due in November 2070. (Reporting by Shamsuddin Mohd in Bengaluru, Federico Maccioni and Yousef Saba in Dubai; Additiponal reporting by Marc Jones in London; Editing by Louise Heavens and David Holmes)