* Death toll from floods rises to 50
* Danger of disease as waters recede
* List of missing runs into hundreds
BELGRADE/SARAJEVO, May 22 (Reuters) - Serbia's agriculture ministry appealed for chlorine bleach, quicklime and disinfectant on Thursday to stem the risk of disease after the worst floods to hit the Balkans in living memory.
The regional death toll ticked up to 50, and may rise further given a list of missing in Serbia that runs into the hundreds.
With temperatures now pushing 30 degrees Celsius (86 degrees Fahrenheit), the smell of decay hung in the air in the worst-affected Serbian town of Obrenovac, 30 km (18 miles) southwest of the capital Belgrade.
"The stench is overpowering," said Belgrade chemical technician Bratislav Cirovic, who volunteered to help with the clean-up. "We wore masks today - the more the waters recede, the more appalling it gets."
Swathes of Serbia, Bosnia and Croatia have been ravaged by flooding and landslides since the heaviest rainfall last week in more than a century caused rivers to burst their banks, sweeping away roads, bridges and homes.
Belgrade was braced for a new floodwave from the River Sava, due on Friday, even as the clean-up began in other areas such as Obrenovac, where most of Serbia's 27 dead were found. Twenty-one people have died in Bosnia and two in Croatia.
In the worst-stricken areas, waters have receded to reveal animal carcasses, food and waste rotting in rising temperatures. The ground shows evidence of a toxic mix of chemicals, fuel and sewage that leaked from industrial firms, sewers, gas stations and storage tanks.
Obrenovac was a closed town, police limiting entry on Thursday to an organised group of shopkeepers allowed in to inspect the damage.
"First we will remove animal carcasses and then we will enter one home at a time to assess what can be salvaged," Predrag Maric, the head of Serbia's Department for Emergency Situations, told Reuters.
"Then we can initiate the drying process, disinfection, extermination of rodents and other pests and only then will people be allowed to come back."
Underscoring the scale of the challenge, Serbia's agriculture ministry issued an appeal for more chlorine bleach, quicklime, protection gear and disinfectants. Serbs have been urged not to consume food and crops from the affected areas.
Visiting Bosnia, the European Union's crisis response and humanitarian aid commissioner warned of the risks to health.
"The most troubling problem today is the large number of dead animals in the water and the mixing of water supplies with polluted water, creating a very serious health risk for populations in these areas," Kristalina Georgieva told reporters.
Bosnia, in particular, has no specialised means to safely incinerate the thousands of farm animals drowned by floodwaters, and has appealed to neighbouring Serbia and Croatia for help.
Georgieva also cited the added danger in Bosnia posed by an estimated 120,000 landmines left over from the country's 1992-95 war and the risk that many may have been shifted by the floodwaters from previously marked minefields.
Late on Wednesday, Serbia's interior ministry appealed to anyone who had found someone they previously reported missing to notify police in order to narrow down search efforts.
The ministry, in a statement, said 798 people had been reported missing, of which 215 had since been located, fuelling speculation that the real death toll may be much higher. "Many turned out to be with their friends and relatives," said Maric. "We're checking each and every report on missing persons."
Both Serbia and Bosnia have appealed for foreign aid to help with the recovery, with some damage estimates for each country in the range of 1 billion euros ($1.37 billion). ($1 = 0.7318 Euros) (Additional reporting by Fedja Grulovic in Obrenovac; Writing by Matt Robinson; Editing by Mark Heinrich)