WPP chief Martin Sorrell said this week that a previously reported decline in PR and public affairs revenue during the first quarter ebbed somewhat in April but the sector continues to lag other units like advertising and media investment.

The London-based conglomerate, which saw PR/PA fall 1.4% to $354M in Q1, said in a trading update June 11 coinciding with WPP's annual meeting that the sector showed "some improvement" in April, but noted that North America and Europe remain "more difficult."

WPP, which includes Burson-Marsteller, Ogilvy PR and Hill+Knowlton, among other units, said it saw continuing growth across all geographies and sectors except PR and PA through April.

Sorrell said WPP is hiring "cautiously" with an April headcount lower than at the start of the year and "responding to any geographic, functional and client changes in revenues – positive or negative." WPP's units employ 165K people.

Several "grey swans" are making clients reluctant to take risks despite strong profits and balance sheets, including the Eurozone crisis, the Middle East, uncertainty in China and BRICs, and "most importantly" the U.S. deficit and sequester," he said.

"All in all, there are enough uncertainties for clients to remain cautious and the focus remains, perhaps unwisely, on cost reduction, rather than revenue stimulation and on liquidity, which explains the recent unrealistic demands for extended payment terms," said Sorrell.