Abu Dhabi's Al Hilal Bank plans to raise $500 million from a capital-boosting Islamic bond issue, with pricing tightening ahead of completion on Tuesday due to investor demand, a document from lead arrangers said on Monday.

Pricing for the transaction, which has a perpetual tenor but can be bought back by the lender after the fifth year, was revised on Monday afternoon to fall in the area of 5.75 percent, the document said. This was inside the 6 percent area guidance given earlier in the day.

Investor orders for the deal, which will boost Al Hilal's Tier 1 - or core - capital, were above $3 billion. Despite the interest, the size of the transaction will not be increased, the document added.

The unlisted Islamic lender, owned by the Abu Dhabi Investment Council, has chosen itself as well as Citigroup , Emirates NBD, HSBC, National Bank of Abu Dhabi and Standard Chartered to arrange the deal.