FIRST Union members will strike today at ANZ branches and contact centres in six of New Zealand's biggest cities in protest at a pay offer and new contracts they said reduce the certainty of their work hours.FIRST announced the strike on Monday, but did not detail when it would happen or in which cities. It said pickets would also be set up outside the biggest branches in Auckland and Wellington and marches staged in both city centres. Workers would also strike in Hamilton, Palmerston North, Christchurch, Oamaru and Dunedin. About 1,300, or 20 per cent, of ANZ's staff in New Zealand are FIRST workers and 96 per cent of union members in the six cities voted for industrial action in protest at a pay offer and a move to more flexible rosters for new staff to work on evenings and on weekends."ANZ is actively promoting a proposal which would leave bank workers with jobs that they cannot plan their lives around, by chopping and changing their days and start times month by month," said FIRST Retail and Finance Secretary Maxine Gay."I'd like (ANZ NZ Chief Executive) David Hisco to come down from his office tomorrow and tell members of our union why he thinks an ANZ staff member with dependent children needs to be put through the stress of having their days and hours changed every month," Gay said.  Gay said workers had been prepared to allow up to 20 per cent of the workforce to be on the flexible hours contracts, but ANZ wanted all new workers to start on the new contracts.ANZ Spokesman Stefan Herrick said the bank was disappointed with the strike action, given the same offer had been made to non-union staff and received positively.Herrick said ANZ expected all branches would remain open and all services would be available. He said the proposal for flexible rosters did not casualise jobs or reduce job security.ANZ planned to open branches on some evenings or on weekends and wanted staff members to be on a roster to take turns, which could not be done under the current agreement, he said."We need a bit of flexibility with some staff so that we can meet the needs of our customers in the best way," Herrick said, noting the flexible work rosters would only be offered to some new employees in branches.Staff on the flexible rosters would work up to 150 hours over a four week period."The union is simply trying to create an issue out of this because they want a higher pay increase than the very competitive 3 per cent and 2.75 per cent that we have offered staff (over two years)," he said.