DUBAI, Aug 30 (Reuters) - Dubai-based Emirates Islamic Bank has priced a $250 million tap of an existing Islamic bond issued in May, the lender said on Tuesday.

The tap was priced at 170 basis points over midswaps, the bank said in a statement, adding the funds were raised from investors in the Gulf, Asia and Europe. The order book was worth $706 million.

Under a tap transaction, a 'new' deal is issued which is, in effect, a copy of an existing bond with the same terms and conditions. However, the pricing is usually adjusted to reflect current market conditions.

Emirates Islamic's tap came off a $750 million five-year sukuk issued on May 23. That deal was priced at 220 bps over midswaps and carried a coupon of 3.542 percent.

The bank's Chief Executive Jamal bin Ghalaita said the tap allowed the lender to benefit from cheaper funds available in the current market conditions, adding the cash would support its long-term growth and development plans.

The sharia-compliant bank, owned by Dubai's largest lender Emirates NBD , said Bank ABC, Dubai Islamic Bank, EMCAP and Standard Chartered arranged the new offering.

(Reporting by Hadeel Al Sayegh; Editing by David French and Susan Fenton) ((Hadeel.AlSayegh@thomsonreuters.com; +971566883310))