Washington (CNN) -- Countries from around the world have offered to help the United States and BP deal with the massive oil spill in the Gulf of Mexico, but several nations' representatives tell CNN that they have not heard back after reaching out to officials.
Seventeen offers of assistance have come from countries and five other offers from international organizations including the European Union and the European Maritime Safety Agency, according to State Department spokesman P.J. Crowley. The assistance includes a range of offers, from oil boom to scientific expertise.
The State Department receives the offers and passes them on to the U.S. Coast Guard-led Unified Area Command (UAC), which includes representatives from BP, the owner of the well. The UAC makes decisions on which offers to accept based on what the immediate needs are -- but the final decision is up to BP, Crowley said.
Three offers, from Canada, Mexico and Norway, have been accepted. All three are major oil-producing countries.
In addition, assistance is coming through private as well as public sources, Crowley said.
One reason BP may not be accepting the offers of assistance is because of cost, some say. Shipping boom from halfway around the world, for example, is expensive.
Other factors, according to a senior U.S. official, include liability for any equipment that might be provided, and support for any crews that might accompany that equipment.
"Offers are being relayed to BP and evaluated based on the needs of responders, what may be in short supply here, what special equipment residing elsewhere may be useful, and what expertise might help," said Coast Guard spokesman Capt. Ron LaBrec. "In addition to general offers of assistance, specific offers include experts in various aspects of oil spill impacts; research and technical expertise; and equipment, including boom, dispersants, oil pumps, and skimmers."
LaBrec said the United States would accept help if determined it is needed "to facilitate the response."
The 17 countries include: Canada, Mexico, Korea, Croatia, France, Germany, Ireland, Japan, the Netherlands, Norway, Romania, Russia, Spain, Sweden, the United Arab Emirates, United Kingdom and Vietnam. Organizations that have offered assistance include the U.N. Office for the Coordination of Humanitarian Affairs, the U.N. Environment Program and the International Maritime Organization.
Canada is providing technical experts, aerial surveillance aircraft, staff, and research and development on methods used in previous spills.
The Norwegian Coastal Authority says approval has been granted to send dispersants as well as two different kinds of boom, one traditional and one designed for stronger currents.
The United Kingdom has stocks of oil dispersant on standby if needed and the Japanese Embassy says it has offered boom.
A team of 30 engineers from the Abu Dhabi National Oil Company has been offered by the United Arab Emirates.
The European Union is coordinating offers through the Civil Protection Monitoring and Information Center in Brussels, Belgium, while individual European countries, such as Germany and Ireland, have offered help directly through the center.