The United States, reacting strongly to reports of Libyan armored columns moving deeper into Chad, yesterday reaffirmed its "strong strategic interest" in preventing Col. Muammar Qaddafi from intervening militarily in other African countries.

Chadian officials admitted that government troops were retreating from the eastern towns of Oum Chalouba and Kalait following fierce Libyan air attacks on Thursday. The State Department confirmed that the insurgent forces of former president Goukouni Oueddei had taken Oum Chalouba and that the bombing was continuing.

"The situation is serious, and we are concerned about it," said State Department spokesman John Hughes. "It's getting a lot of attention."

Western diplomats in the capital, Ndjamena, said that a column of 200 Libyan armored vehicles was within three miles of Faya Largeau, a northern stronghold that has been subjected to almost a week of Libyan air raids.

They also said that another rebel column of Soviet-built T62 and T72 tanks was reported about 150 miles northwest of Faya Largeau.

Qaddafi, one senior State Department official said yesterday, "seems determined to destroy" Chad President Hissene Habre.

The United States, the official added, hopes that a stronger French response to the crisis, in the form of a display of air power to deter the Libyans, may force Qaddafi to back down.

"He's a bully," the official said, "but he's a chicken."

"The United States," White House spokesman Larry Speakes said, "has a strong strategic interest in assuring that Qaddafi is not able to upset governments or to intervene militarily in other countries as is currently happening in Chad.

"If Libya or Libyan-supported forces were to gain control of Chad, close U.S. allies such as Egypt and Sudan would be seriously concerned about their own security," Speakes said. "Other states in the region would also be deeply worried."

Officials indicated that there were no plans to increase U.S. naval activity off Libya, but Speakes said he did not preclude ships entering the Gulf of Sidra, which Libya claims as its territorial waters.

"I won't say we won't proceed where we would like to in the gulf," he added.

One report yesterday, quoting diplomats in Cairo, said that in Libya all military leave was canceled and teachers and students were ordered to report to barracks as part of a general mobilization. Libya, however, has denied repeatedly that it is involved in Chad.

President Reagan already has authorized $25 million in emergency aid to the Habre government, and 30 U.S. Redeye and Stinger antiaircraft missiles and three Army trainers arrived in Ndjamena on Wednesday.

U.S. support for Habre was also underlined yesterday in a meeting between President Mobutu Sese Seko of Zaire and Defense Secretary Caspar W. Weinberger, Pentagon officials said. Mobutu, who has sent 2,000 troops and six aircraft to Chad, ends a six-day working visit to Washington today.

The State Department has set up a Chad Working Group to deal with the crisis, and one senior official said part of the U.S. effort would be devoted to informing African governments of the extent of Libyan intervention in the affairs of other countries on the continent.

Although publicly praising the French role in bolstering Habre, U.S. officials say privately that the socialist government of President Francois Mitterrand must do more to convince Qaddafi of the West's resolve to keep him out of Chad.

"Our judgment," one official said yesterday, "is that the Libyans will test French resolve until they get an answer."

In Montreal yesterday, Sen. Gary Hart (D-Colo.), a Democratic presidential candidate, said he would oppose any major U.S. military role in aiding Chad in its fight against the Libyan-backed rebels.

"I would not want to see a significant U.S. military presence there," Hart told a union audience.