Senate Foreign Relations Committee leaders have urged President Reagan to overcome administration infighting and submit for ratification two arms control agreements negotiated with the Soviet Union in the mid-1970s.

They said in a letter sent to the White House Thursday that ratification of the two treaties would "demonstrate the seriousness of our mutual commitment to arms control" and help prepare the way for success in the forthcoming strategic arms control talks.

Their letter cited testimony of Arms Control and Disarmament Agency Director Eugene Rostow who said that in trying to resolve the internal dispute over ratification he had met "a profound stone wall which is very difficult to deal with."

An administration official familiar with the dispute said Friday that some officials in the Pentagon have opposed ratifying the two agreements, negotiated in 1974 and 1976. He said there appears to be no current intent to submit them to the Senate for ratification.

The letter to Reagan was signed by Sen. Charles H. Percy (R-Ill.), chairman of the committee, Sen. Claiborne Pell (R.I.), the ranking Democrat, and two committee members, Sen. Alan Cranston (D-Calif.) and Sen. Larry Pressler (R-S.D.).

The agreements in dispute are the Threshold Test Ban Treaty, which prohibits underground testing of nuclear devices with an explosive power of more than 150 kilotons, and the Peaceful Nuclear Explosions Treaty, which would permit controlled development of nuclear devices for large-scale construction projects such as canal building.

The second agreement, the committee members said, allows "precedent-setting" provisions for verification of the size of explosions, including on-site inspection. "No other U.S.-Soviet agreement has such provisions," it observed.

The letter noted that former president Gerald R. Ford has endorsed both treaties, as have Rostow and Undersecretary of Defense Fred C. Ikle.