Workers on Monday disrupted commuter transport in parts of Germany as the trade union Verdi staged warning strikes in a bid to get public sector employers to drop their refusal to offer a pay rise. The strikes precede a second round of negotiations due to take place on Wednesday. Affected by Monday's stoppages were bus and tram services in the Munich area, as well as in central Hesse, including Frankfurt, and Potsdam, near Berlin. Also delayed were trash collection services in several locations. The government is arguing that, given its significant budget shortfalls, it cannot offer higher pay this year. Verdi officials said they are planning a major disruption of air traffic at the Frankfurt International Airport on Tuesday.