By Lucia Mutikani

WASHINGTON (Reuters) -U.S. producer prices increased solidly in August, leading to the biggest annual gain in nearly 11 years, suggesting that high inflation is likely to persist for a while as the unrelenting COVID-19 pandemic continues to pressure supply chains.

There are, however, signs that inflation could be nearing its peak, with the report from the Labor Department on Friday showing underlying producer prices rising at their slowest pace in nine months in August. High inflation is eroding households’ purchasing power, contributing to the downgrading of economic growth estimates for the third quarter.

“Inflation continues to see the impact of pandemic effects including strong demand and supply constraints,” said Rubeela Farooqi, chief U.S. economist at High Frequency Economics in White Plains, New York. “The demand impact will likely fade over coming months. But there is more risk from supply chains, if they continue to be disrupted by virus outbreaks.”

The producer price index for final demand rose 0.7% last month after two straight monthly increases of 1.0%. The gain was led by a 0.7% advance in services following a 1.1% jump in July.

Trade services, which measure changes in margins received by wholesalers and retailers, accounted for two-thirds of the broad rise in services. Goods prices jumped 1.0% after climbing 0.6% in July. In the 12 months through August, the PPI accelerated 8.3%, the biggest year-on-year advance since November 2010 when the series was revamped, after surging 7.8% in July.

Economists polled by Reuters had forecast the PPI gaining 0.6% on a monthly basis and rising 8.2% year-on-year.

U.S. stocks opened higher. The dollar was steady against a basket of currencies. U.S. Treasury prices were lower.

Though surveys from the Institute for Supply Management this month showed measures of prices paid by manufacturers and services industries fell significantly in August, they remained elevated. Factories and services providers still struggled to secure labor and raw materials, and faced logistics delays.

This was corroborated by the Federal Reserve’s Beige Book report on Wednesday compiled from information collected on or before Aug. 30 showing “contacts reported generally higher input prices but, as with labor, they were mostly concerned about getting the supplies they needed versus the price.”

Very low inventory levels because of the supply bottlenecks have allowed producers to easily pass on the higher costs to consumers. The Fed’s preferred inflation measure, the core personal consumption expenditures price index, increased 3.6% in the 12 months through July after a similar gain in June.

High inflation and supply constraints, which tanked motor vehicle sales in August, have prompted economists to slash their third-quarter gross domestic product growth estimates to as low as a 3.5% annualized rate from as high as 8.25%. The economy grew at a 6.6% rate in the second quarter.

“The danger with inflation is once prices go up, they don’t go back down and the economy and producers and consumers all have to live in a costlier world where many don’t have the means to do more than just barely survive,” said Chris Rupkey, chief economist at FWDBONDS in New York.

But inflation is likely nearing its peak. Excluding the volatile food, energy and trade services components, producer prices rose 0.3%, the smallest gain since last November. The so-called core PPI shot up 0.9% in July.

In the 12 months through August, the core PPI accelerated 6.3%. That was the largest rise since the government introduced the series in August 2014 and followed a 6.1% increase in July.

(Reporting by Lucia Mutikani;Editing by Chizu Nomiyama and Andrea Ricci)