(Adds detail, background, writes through)

By Maggie Fick

CAIRO, May 17 (Reuters) - Egyptian construction and fertiliser group OCI OCI.NV said its core earnings were flat in the first quarter, citing lower construction margins and reduced output at its Egyptian plants due to interruptions in supplies of natural gas.

The Dutch-listed parent of Orascom Construction Industries (OCI) OCIC.CA said output from its Egyptian plants was reduced by the gas supply reductions, which it linked to a tax dispute between its subsidiary OCI and the Egyptian authorities.

It gave no figure for core profit or EBITDA (earnings before interest, taxes, depreciation and amortisation).

The group, one of Egypt's biggest companies, also said on Friday it estimated first-quarter consolidated earnings had increased by between 10 and 20 percent from last year, but again gave no figures.

It said its Egyptian plants "faced natural gas supply curtailments" during the first quarter, but that since a settlement agreement on April 30, gas utilisation rates had increased.

OCI, run by one of Egypt's most prominent Christian families, the Sawiris, said last month the Egyptian tax authority had exonerated it of wrongdoing after it agreed to pay 7.1 billion Egyptian pounds ($1 billion) to resolve a tax dispute.

The dispute stemmed from the company's plan to delist from the Egyptian bourse, a move which was resisted by the country's Islamist-led government.

OCI NV, which already owns about 70 percent of the Egypt-listed shares, had on Tuesday cut the price of its tender offer for the delisting without giving a reason for the reduction, though analysts said it was not a surprise after a fall in the price of the Cairo-listed stock. ID:nL6N0DY0RO ($1 = 6.9760 Egyptian pounds)

(Editing by David Holmes)

((maggie.fick@thomsonreuters.com)(+20 101 837 3117))

Keywords: EGYPT OCI/