A traffic sign is pictured in front of the skyline of the the Canary Wharf financial district in London October 21, 2010. REUTERS/Luke MacGregor

LONDON (Reuters) - The number of profit warnings issued by British companies jumped to 75 in the third quarter, the biggest quarterly rise in almost six years as economic pressures weighed on retailers and support service companies, business services group EY said on Sunday.

The spike came straight after one of the biggest falls recorded in the previous quarter, when there were 45 warnings, and is significantly ahead of the average of 62 in the third quarter, EY said.

“Summer brought more mixed fortunes for UK plc with the contrast between accelerating overseas markets and the slowing UK economy increasing,” said EY’s head of restructuring Alan Hudson.

“Many businesses besieged by pricing pressures before Brexit are also now feeling the brunt of rising domestic uncertainty and rising costs.”

Retailer Dixons Carphone DC.L and construction and support service firm Carillion CLLN.L were two of the biggest companies to warn in the period.

The warnings have showed no sign of slowing in October, with park operator Merlin Entertainments MERL.L, engineer GKN GKN.L, workspace group IWG IWG.L and another support services company, Interserve IRV.L, all downgrading forecasts.