Eurozone economic activity managed a small gain in July despite Britain's shock vote in June to quit the European Union, a closely watched survey showed Wednesday.

Data monitoring company IHS Markit said revised figures for its Composite Purchasing Managers Index (PMI) for July came in at 53.2 points, up from 53.1 points in June.

The original report put the July PMI at 52.9 points, an 18-month low but was still well above the 50-points boom-or-bust line.

The PMI measures companies' readiness to spend on their business and so gives a good idea of how the underlying economy is performing.

Markit chief economist Chris Williamson said the figures suggested the Brexit vote had had little impact so far but growth remained modest at best.

"A welcome uptick in the final PMI numbers presents a slightly better picture than the slowing signalled by the earlier flash reading and is especially encouraging as it suggests the region saw little overall contagion from the UK's Brexit vote," Williamson said in a statement. 

"However, the survey is still indicating only a modest 0.3 percent quarterly rate of economic growth at the start of the third quarter," he said.

The 19-nation eurozone economy grew 0.3 percent in the three months to June, down sharply from 0.6 percent in the first quarter.

Williamson said a continued slowdown likely means the European Central Bank will have to take additional stimulus measures.

Current growth was supported by a strong showing in Germany, Europe's biggest economy, but France "continued to stagnate, acting as a significant drag on the region," he said.