Northern Ireland's private sector output has dropped for the third month in a row, research from Ulster Bank suggests.

The bank conducts a monthly survey of private sector activity in what is considered a reliable indicator of the economy.

May saw a fall in new business orders, staffing levels and overall output.

Unlike in previous months, there was a fall in output of all four sectors of the economy.

This is the first time that this has happened in six years.

Richard Ramsey, the bank's chief economist, said: "It's not just manufacturing that is weakening; all four sectors saw falling output for the first time in six years."

'Brexit stockpiling'

"Construction firms have now reported falling orders for nine successive months and retailers have been reporting falling sales every month in 2019 to date."

Mr Ramsey said the global slowdown which had been impacting other economies was now clearly evident in Northern Ireland.

"Brexit stockpiling by manufacturing companies had been inflating the performance of local firms in recent months," he said.

"Now that the rapid phase of stockpiling activity has passed, the latest PMI (purchasing managers' index) data reflects the reality of current demand."

But the survey suggests expectations about the year ahead have improved, firms expect output to have risen in a year's time.

Mr Ramsey said: "Whilst firms expect challenges in the short-term - citing Brexit as one of the key factors - their expectations for the longer-term are marginally better."