BERLIN, July 29 (Reuters) - German defence contractor Rheinmetall reported a stronger-than-expected ‌second-quarter operating profit on Wednesday ‌as booming demand for military equipment helped drive ​a sharp increase in revenue across all business segments.

Operating profit climbed to €562 million ($640 million), beating market expectations of ‌about €470 million, ⁠while revenue rose nearly 70% from a year earlier to ⁠about €3.3 billion.

Rheinmetall had already said on July 2 that it expected revenue ​growth of ​more than ​60% for the ‌reporting period.

The company cautioned, however, that operating free cash flow is expected to be significantly negative in the quarter because advance payments were shifted ‌into later periods.

The company's ​order backlog exceeded €80 billion ​in the ​quarter after it recorded €11.37 ‌billion in new contract ​awards and ​programmes, including one from the German military for loitering munitions.

The company will ​publish detailed ‌half-year results on August 6.

($1 = 0.8782 ​euros)

(Reporting by Miranda Murray, editing ​by Thomas Seythal)