The growth in the non-oil business sector in the United Arab Emirates (UAE) slowed down slightly in March, a survey showed on Wednesday as supply constraints caused by shipping disruptions in the Red Sea contributed to backlogs.

The seasonally adjusted S&P Global UAE Purchasing Managers' Index (PMI) slowed to 56.9 in March from 57.1 in February but remained firmly above the 50 mark, signaling growth.

The output subindex eased to 62.7 last month from February's near five-year high, but growth momentum remained strong, lifted by new business and projects in the pipeline.

The backlogs of work subindex rose to its joint highest level of 59.8 – previously recorded in June 2018 – from 56.4 in February. Contributing factors included strong demand, administrative delays and Red Sea disruption to shipments, the survey said.

"The overall picture for the UAE non-oil private sector remained rosy at the end of the first quarter," said David Owen, senior economist at S&P Global Market Intelligence.

"While the surge in backlogs is concerning as an indicator of business health, the pent-up demand should support activity growth for even longer once these issues are resolved."

The new orders subindex rose to 61.5 in March from 60.4 in February, signaling continued strong demand.

Optimism about the outlook among non-oil businesses increased in March to its best level in six months, the survey showed.