BERLIN (Reuters) - The German economy lost some growth momentum in the second quarter after a strong performance in the first three months of the year, the Economy Ministry said on Thursday, citing weaker private consumption and weaker-than-expected construction.

It added that the German economy remained robust despite increased external risks largely linked to Britain's vote in June to leave the European Union.

"Because of mild weather, construction was much higher than usual in winter," the ministry said in its monthly report. "Therefore the spring upturn was significantly weaker."

The German economy grew by 0.7 percent in the first quarter, driven mainly by increased government spending and rising private consumption.

Preliminary second-quarter growth figures are due to be published on Friday. A Reuters poll of economists predicts that Europe's largest economy expanded by 0.2 percent in the April-June period. <ECONDE>

(Reporting by Joseph Nasr; Editing by Michelle Martin)