MADRID (Reuters) - The world's biggest apparel retailer Inditex said average shipping times have been delayed by about a week by the Red Sea crisis, as container ships carrying its products avoid the Suez Canal and travel around the southern tip of Africa.

Yemen's Houthis have kept up a relentless campaign of attacks on vessels in one of the world's busiest shipping lanes since November, in what they say is solidarity with the Palestinians during Israel's war with Hamas in Gaza.

"Shipping costs may have risen as a result of higher fuel consumption and the extraordinary cost overruns," Inditex said in its annual report on Thursday.

"Our operations have not been significantly impacted by this situation so far," it added.

Inditex said the shipping disruption has so far been the main impact on its business from the conflict in the Middle East.