In a pointed demonstration of sympathy for Romania's increased show of independence from the Soviet Union, President Carter yesterday instructed Treasury Secretary W. Michael Blumenthal to visit Bucharest today and Saturday for talks with President Nicolae Ceausescu.

Blumenthal, who has been on a European tour that included a stop in the Soviet Union, was told to add Romania to his itinerary for what White House press secretary Jody Powell called "discussions on bilateral and international relations."

Powell declined to say whether the visit is related to the growing rift between the Kremlin and Ceausescu, who has long played a maverick's role among Moscow's Warsaw Pact allies.

In a recent series of events tied to the 60th anniversary celebrations of modern Romania, Ceausescu has gone to extraordinary lengths to bring his differences with the Soviets into the open.

These have included Romania's balking at a Soviet demand for Warsaw Pact members to increase their defense budgets, refusal to sign a Warsaw Pact statement condemning the U.S.-inspired Middle East peace talks and defiance of Soviet policy positions toward such countries as Cuba and Vietnam.

In a recent emotional speech, Ceausescu underscored these differences with a plea for "the sacred right of each nation to decide its own destiny without outside interference."

Despite the White House's reluctance to publicly connect Blumenthal's visit to the Romanian-Soviet rift, administration sources said privately that the trip is intended as "a show of the flag" to demonstrate U.S. sympathy for Ceausescu's position.

That message came through clearly in the guidance provided by the White House and State Department to spokesmen replying to reporters' questions about the Blumenthal visit.

The guidance accompanying the announcement of the visit referred to the "steady improvement" in U.S.-Romanian relations and added: "We value these relations as we do Romania's constructive role and independent policy on many important international problems."

It continued: "Secretary Blumenthal's visit will serve to reaffirm these longstanding elements of our policy toward Romania."

In addition, when the State Department spokesman Hodding Carter, was asked about the possibility of overt Soviet moves against Romania, he replied:

"We see no reason to expect this. While a member of the Warsaw Pact, Romania is a sovereign state and has the right to determine its own policies according to its own needs. This is the Romanian view, and we, for our part, respect it."