Two additional F-16I fighter jets were found in recent days to have unusually high concentrations of carcinogenic material, the IAF revealed early Tuesday morning, raising the total of such cases to three. IAF chief Maj.-Gen. Elazar Shkedy decided on March 21 to ground all F-16I training flights (the plane will continue to be used in necessary operations) after formaldehyde was found in the cockpit of one of the aircraft. IDF sources said the air force was no closer to discovering the precise cause of the carcinogenic leak and was consequently maintaining the ban on training flights. So far, 20 planes have been checked for the material. Each inspection includes several days of lab tests and at least one hour of work on the aircraft. Despite the ongoing inspections, the IAF has decided to continue receiving F-16Is from Lockheed Martin. Four planes arrived in Israel over the weekend. Upon arrival, the planes began undergoing tests to determine if they contained high concentrations of formaldehyde. In addition to these inspections, the IAF has conducted tests on its fleet of F-15Is, which came up clear of high formaldehyde concentrations. Meanwhile, Israel has also been in touch with a number of countries that have the F-16I, to discuss the technical issues. Singapore has begun to test its planes as well, Channel 1 reported Tuesday night. The F-16I is also in operation in Poland, Greece and the US. The IDF has been receiving about two planes a month since 2004 and is expected to receive the complete 102 it has ordered by the end of the year.