(Adds details on timeline, size expectations)
By Davide Barbuscia
DUBAI, April 4 (Reuters) - Saudi Aramco (IPO-ARMO.SE) has extended the bookbuilding process for its debut local currency sukuk by one day beyond the original deadline of April 3, sources familiar with the matter said on Tuesday.
The books are expected to close on Tuesday, with final allocations likely to take place on Wednesday, said a banker working on the deal.
The reason behind the extension is that some accounts needed extra time to obtain internal approval before placing their orders. The size of the deal is likely to be between $2 billion- and $4 billion-equivalent, the banker added.
The sukuk is Aramco's first attempt to diversify its funding sources in an era of low international oil prices. The oil giant, which Saudi officials have valued at over $2 trillion, is preparing to sell up to 5 percent of its shares in an initial public offer expected to take place in 2018.
Aramco started gathering orders for its debut sukuk - part of a 37.5 billion riyal ($10 billion) programme - on March 27, a document issued by the banks leading the transaction showed.
According to the original timeline, the last date for orders and allocations was expected to be April 3, with settlement expected on April 9.
The floating rate Islamic bond has a seven-year maturity and offers 25 basis points over the six-month Saudi Arabian Interbank Offered Rate (SAIBOR).
Alinma Investment, HSBC Saudi Arabia, NCB Capital and Riyad Capital are the joint lead coordinators. They are joined by GIB Capital, Samba Capital and Saudi Fransi Capital in dealer roles.
$1 = 3.7500 riyals Editing by David Evans