Mustard gas contamination in the Baltic Sea is closer to the Polish coast than originally thought, within just a few hundred feet, researchers say.

Scientists at Poland's Military University of Technology, after conducting a thorough examination of samples from the bottom of the Gulf of Gdansk, found traces of mustard gas in the shallow Bay of Puck, broadcaster TVN24 reported Saturday.

Stanislaw Popiel of the institute, known by its Polish acronym WAT, said the contamination -- a result from the dumping of thousands of tons of chemical weapons onto the ocean bed after World War II -- was found only a few hundred meters from the Polish presidential resort near the port of Gdynia.

"We found contamination in both the Gulf of Gdansk and in the Bay of Puck," Popiel said.

The analysis found contamination both in the greater Gulf of Gdansk, as well as in the inner Bay of Puck adjacent to Hel Peninsula, a 20-mile-long sand bar peninsula in northern Poland separating the bay from the open Baltic Sea.

"Where is the contamination coming from? It's hard to say," he added.

WAT and the Polish Naval Academy are taking part in the European Union's Chemsea project, which is seeking to map and characterize the Baltic Sea dumping sites, where at least 15,000 tons of chemical munitions were disposed of.

"If this data is confirmed, you either have facilities in the Gulf of Gdansk which no one ever knew of, or there is a far greater spread of these compounds in the sediment than we thought," Jacek Beldowski of the naval academy and coordinator of the Chemsea effort told TVN24.

Scientists say the residual mustard gas in the Baltic Sea can be dangerous not only for the marine fauna and flora, but also for humans. Experts are urging fishermen and people walking along beaches to stay away from rusty barrels and ammunition they may find -- they can still be dangerous even after many decades.

Exposure to stinging mustard gas mainly causes skin burns, but the substance is also poisonous. If it enters the body, it can cause genetic mutations and cancerous tumors over time.

Shortly after the end of World War II, British and Russian Allies forces decided under an international agreement to sink tons of German chemical weapons and precursors into the Gotland Deep, an 800-foot-deep basin in the Baltic Sea between Sweden and the Baltic countries.

The chemical warfare agents contained in the munitions include so-called blister gases like mustard gas or nitrogen mustard, tear gases, nose and throat irritants such as phosgene and nerve gases such as tabun.

These dumped chemical munitions may also contain certain amounts of explosives. It is assumed that the chemical munitions dumped in the Baltic Sea contained roughly 15,000 tons of chemical agents.

The EU hopes to develop guidelines to reduce potential threats to the environment and fishermen and is drawing up region-wide contingency plans to deal with cases of leakage.