Two Thai policeman were killed and 13 people wounded in gun and grenade attacks overnight, threatening efforts to forge a deal on ending nearly two months of anti-government protests that have undermined the economy, Reuters reported. Prime Minister Abhisit Vejjajiva has put forward a plan to end the rallies that have crippled Bangkok and scared off tourists, but it remains in limbo as talks drag on over the details, including a proposed early election in mid-November. The "red shirt" protesters denied involvement in the attacks and were quick to condemn the violence, which could add to pressure on Abhisit from the Bangkok middle classes and traditional elite to take a tougher line with the protesters. The movement's leaders said they were committed to the reconciliation plan and were working on their own proposals to present to the government, which they guaranteed would be ready no later than May 15. "This should be a peaceful solution. There are some issues on which we agree with the government, and some in which we disagree," a protest leader, Nattawut Saikua, told reporters. "Our proposal will be flexible. We are ready to listen... because we want to make way for a conciliatory atmosphere." Police and an official at the state-run Erawan Medical Centre said the first policeman was killed by a gunman on a motorcycle in a drive-by shooting just before midnight, and the second in a series of suspected grenade blasts around two hours later. The attacks took place in the Silom Road area of the capital guarded by soldiers and packed with hotels and bars popular with tourists. The area is close to the entrance to a fortified encampment held by the protesters since early April. Abhisit ordered a tightening of security in the area after a meeting on Saturday with Deputy Prime Minister Suthep Thaugsuban and the government's crisis control group, the Centre for the Resolution of the Emergency Situation (CRES). "CRES believe there are a group of people who don't want the protest to stop," government spokesman Panitan Wattanayagorn told reporters. The stand-off has paralysed the commercial heart of the capital for nearly two months, but its roots stretch back to the prime ministership of Thaksin Shinawatra -- a populist tycoon ousted in a 2006 military coup -- and the deep social divisions it exposed between Thailand's traditional elite and rural masses. The temperature of protests had been cooling after a week of calm following Abhisit's offer to dissolve parliament in the second half of September ahead of an election on Nov. 14 as part of a plan to end a crisis that has now killed 29 people. STILL HAGGLING But rival camps were still haggling over the details of the plan, with the mostly rural and urban poor red shirts refusing to leave their camp in central Bangkok, where sleek malls and luxury hotels have been forced to close their doors since April 3. "We want Abhisit to withdraw troops from this area. He has to show sincerity by lifting a state of emergency first," said another protest leader, Weng Tojirakarn. Thousands of protesters rallied on Saturday inside the heavily barricaded camp covering 3 sq km (1.2 sq miles). Leaders said thousand more were traveling to Bangkok from their northeastern heartland on Saturday. Government spokesman Panitan said security forces would try to stop more people joining the protest. Friday's shooting took place just 50 metres from the fortified front lines of the red shirt encampment in a business district packed with hotels, banks and offices close to the city's famous Patpong go-go dancing bars. No arrests were made. Reuters reporters heard three loud blasts in the same area about two hours after the shooting. A hospital official said 13 people were wounded in the violence, three civilians, three soldiers and seven police. The wounded included two "multi coloureds" protesters among a group of several dozen who had gathered to voice their opposition to the red shirts. -- SPA