ANKARA/ISTANBUL (Reuters) - Turkey's deputy prime minister said on Monday the armed forces could be called up if needed to help quell popular protests that have swept Turkish cities in the last two weeks, the first time the possibility of a military role has been raised. Bulent Arinc made the remarks in Ankara, where 1,000 striking trade union workers faced off briefly against police backed by several water cannon, before police retreated and the crowd left. In Istanbul, the cradle of protests that have presented Prime Minister Tayyip Erdogan with the greatest public challenge to his 10-year leadership, several hundred union members also marched in sympathy with anti-government demonstrations. They were prevented from entering Taksim Square, the focal point of the unrest, but after workers had moved off, between 200 and 300 mainly young protesters, some of them throwing stones from slingshots, fought with police. The violence was minor compared with the weekend, which saw some of the fiercest clashes so far when police fired teargas and water cannon to clear thousands of people from the square. Our police, our security forces are doing their jobs. If it's not enough, then the gendarmes will do their jobs. If that's not enough ... we could even use elements of the Turkish Armed Forces, Arinc told Turkey's state-run TRT television. Any use of the army would be a dramatic step in Turkey, where Erdogan has pushed through democratic reforms including taming a military that toppled four governments in four decades. There were also clashes on Monday in the city of Eskisehir, around 200 km (120 miles) southeast of Istanbul, where police used teargas and water cannon to disperse crowds and cleared away hundreds of tents, the Dogan news agency reported. Monday's union marches were peaceful and small, and, while it was unclear how many of the 850,000 public workers answered union calls to strike, there were no signs of major disruption. What began late in May as a protest by environmentalists upset at government plans to build on a public park adjoining Taksim has grown into a movement against Erdogan, who opponents say is overbearing and meddles in their personal lives.