Orders for Saudi Aramco's debut international bonds topped 85 billion U.S. dollars, sources familiar with the matter said, a record-breaking vote of market confidence for the oil giant.

The state-owned oil giant is marketing a U.S. dollar-denominated debt issue split into six tranches with maturities ranging from three to 30 years.

Before opening the books earlier on Monday, the Aramco issue – which will be priced on Tuesday – had already attracted over 30 billion U.S. dollars in demand, Saudi Energy Minister Khalid al-Falih said.

Aramco's bonds have attracted demand from a wide range of investors, as state-owned Aramco's vast profits would put its debt rating - if unconstrained by its sovereign links - in the same league as independent oil majors like Exxon Mobil and Shell.

The issue follows on the heels of Aramco's planned 69.1 billion U.S. dollars acquisition of a 70 percent stake in petrochemicals firm Saudi Basic Industries Corp (SABIC) from the Saudi sovereign wealth fund, a deal that many see as a transfer of government funds aimed at boosting the Saudi Crown Prince's economic agenda.

"This bond is being issued for two reasons: to establish Aramco's status as an independent corporate identity and to enable the transfer of wealth out of the company," said Marcus Chenevix, an analyst at MENA and global political research at TS Lombard.

Aramco, however, said the bond issue was not linked to the SABIC acquisition, and many see it as a relationship building exercise with international investors ahead of its planned initial public offering, scheduled for last year and then postponed to 2021.