* STOXX 600 posts monthly loss of 5.7%; worst since Jan, 2016
* Firms with Mexico exposure hit, Spanish lenders decline
* Auto sector drops, sector index plumbs near 5-month closing low
* Utilities, real estate stocks en vogue; investors rush for cover (Recasts throughout, adds quote and graphic, updates to close)
By Aaron Saldanha
May 31 (Reuters) - European stocks tanked on Friday, with auto-makers hit especially hard, after U.S. President Donald Trump widened the scope of his trade wars by threatening to impose new tariffs on Mexican imports.
Investors exited riskier equity positions and moved to safer ground, sending European defensive stocks higher and yields on German bonds to record lows.
The pan-Europe STOXX 600 fell 0.8% on the day to close out May with a 5.7% slide, its worst monthly loss since January 2016.
"President Donald Trump is playing a Game of Thrones with both foreign and domestic adversaries," Ed Yardeni, president and chief investment strategist at Yardeni Research, wrote in a note.
"Since he is the president of the world's greatest economic and military power, he claimed that he will consummate lots of deals with them that will greatly benefit the U.S. in short order," said Yardeni, adding that "the results have been mostly disappointing so far."
Germany's trade-sensitive DAX fell 1.5% to an about five-month closing low. French stocks slid 0.8%, matching their London peers.
Trump's move hit European stocks exposed to Latin America's second largest economy. Madrid-listed banks Santander, Sabadell and Bilbao, all of whom have a sizable presence in Mexico, slid between 2.4% and 4.1%.
Carmakers and their suppliers shed 2%, while Fiat Chrysler and Volkswagen - which import cars to the U.S. from Mexican plants - shed 4.8% and 2.6% respectively.
During May, tariff-exposed auto-stocks have greatly underperformed the STOXX 600, which itself has lagged the S&P 500.
Milan-listed stocks fell 0.7%, with local banks matching that decline. The country's lenders were hit by the Bank of Italy warning that public debt could rise more than forecast this year.
Frankfurt-listed Wirecard tumbled 8.7% after a Handelsblatt report on an investigation by authorities into fraudulent transactions in the sector.
Utilities edged 0.2% higher, while real estate stocks - a refuge for investors at times of tariff turmoil - rose 0.6%.
Athens-traded stocks provided a rare spot of optimism on the day, rising 1.5% to a near 13-month peak. The index posted a 7.4% gain for May, aided by news of snap elections being called.
Reporting by Aaron Saldanha in Bengaluru; Graphic by Susan Mathew and Aaron Saldanha; Editing by Andrew Heavens