The Purchasing Managers Index (PMI) is a closely watched economic indicator, but the value of this data has been called into question, with one economist telling CNBC it is wildly exaggerated.

Several pieces of euro zone PMI data were released on Monday. Spanish manufacturing PMI for June slipped to 54.7 from 55.4 in May, while the headline euro area manufacturing PMI came in at 57.4 for June, its highest reading since April 2011. Generally, a reading of 50 or above indicates the sector is expanding.

However, Paul Donovan, global economist and managing director at UBS Wealth Management, says the data is wildly exaggerated.

"We do not have 3.5 or 4 percent growth in Europe. We are not going to get 3.5 or 4 percent growth in Europe. That's what the PMI numbers have been technically implying," he told CNBC's Squawk Box on Monday.