SAIGON. Feb. 9-An American firm is ?he ?? to begin construction this month of three new blocks of isolation cells on the penal island of Con Son. Each of the three blocks will contain ?? ?ells. The new construction will allow Con Son officials to drastically increase the number of prisoners held under "tiger cage" conditions, one American who is familiar with the project claims.

The new "tiger cages" will be built by the firm of Raymond. Morrison, Knudsen, Brown, Root and Jones (RMK-BRJ) under a $400,000 contract. The funds will be provided by MACCORDS (Military Assistance Command Civil Operations for Revolutionary Development Support), the American paramilitary economic aid program here.

Priority

The isolation compound will be a "Top Ten Project." one person familiar with RMK-BRJ priorities said. As such it will receive priority in the routing of supplies and assignment of personnel.

The Vietnamese authorities already have one cell block under construction. A January 7 memo describing the job to be done at Con Son states that the new construction is to be

"similar to the isolation cell block currently under construction as a self-help project."

Prison labor will be used in the construction. Skilled prison labor will be paid 200 plasters (72 cents) per week and unskilled labor will receive 150 plasters (55 cents) a week. There is some concern that the prisoners will not be in good enough physical condition to do a "full day's work." Discussion is under way about the possibility of providing special extra rations for those who work on the project.

Con Son prison was in the news last July when two American congressmen found the "tiger cages" which had been kept secret for years by the Vietnamese government. The "tiger cages" visited by Congressmen William Anderson (D-Tenn.) and Augustus Hawkins (D-Calif.) were built by prison labor in 1939 under the direction of the French.

Congressman Anderson wrote to President Nixon following that visit: "The Tiger Cage imprisonment of human beings and the savage mistreatment of these prisoners are outrageous contradictions to the minimal standards of political decency we, as a free American people, should establish as a condition of our aid and friendship to any nation."