MEXICO CITY—Private economists surveyed in August by the Bank of Mexico joined the central bank and the Finance Ministry in lowering their economic growth estimates for 2015, citing volatility in international markets as the main risk to growth, survey results showed Tuesday.

Gross domestic product is expected to expand 2.3% this year and 3% in 2016, according to the median estimates of 38 analysts polled last month by the central bank, down from 2.5% and 3.2%, respectively, in July.

A sluggish first half of the year, especially in the industrial sector, led the Bank of Mexico last month to cuts its 2015 GDP forecast to a range of 1.7%-2.5%, while the Finance Ministry lowered its estimate to 2%-2.8% from 2.2%-3.2%.

GDP grew 2.4% in the first half of the year, following 2.1% growth in 2014.

The main perceived obstacles to Mexican economic growth in the August survey were international financial instability and weakness in external markets, followed by lower oil production in Mexico. Those issues overtook problems of public security in Mexico and weakness in the domestic market, which had been the most cited causes of concern for the past year.

The slow economic growth has helped keep inflation below the central bank's 3% target, with only limited impact on prices from the peso's recent slide to its weakest ever level against the U.S. dollar. The Bank of Mexico, concerned that the currency depreciation could eventually derail its efforts to keep inflation near its 3% target, has used dollar sales to contain exchange rate volatility while keeping its benchmark interest rate at a record low 3%.

The central bank is widely expected to follow any interest rate increases by the U.S. Federal Reserve with increases of its own.

Exchange rate expectations saw wide changes in the August survey of economists, who see the peso ending the year at 16.40 to the dollar, compared with a 15.60 forecast in July's poll, while consumer-price inflation expectations remained stable around 2.8% for 2015 and 3.4% for 2016.

Write to Anthony Harrup at anthony.harrup@wsj.com

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(END) Dow Jones Newswires

September 01, 2015 11:35 ET (15:35 GMT)