FRANKFURT (Reuters) - Prosecutors in the German city of Braunschweig said they had widened their probe into diesel emissions cheating, with 21 current and former Volkswagen <VOWG_p.DE> staff under investigation.

As part of the probe, offices and private residences in the German state of Lower Saxony were searched, prosecutor Klaus Ziehe said on Tuesday.

In March, prosecutors in Braunschweig said 17 current and former VW staff were being investigated.

German newspaper Handelsblatt was first to report that prosecutors had widened their probe.

In June, prosecutors launched a probe against former Volkswagen Chief Executive Martin Winterkorn and current VW brand chief Herbert Diess to investigate their role in possible market manipulation related to the carmaker's emissions scandal.

At the time, the prosecutor's office said "sufficient real signs" had emerged that Volkswagen may have failed in its duty to disclose it had cheated emissions tests in a timely manner.

(Reporting by Jan Schwartz; Writing by Edward Taylor and Adrian Croft)