Six American diplomats who escaped from Tehran after hiding at the Canadian Embassy returned secretly to the United States yesterday and were expected to spend several days in carefully guarded seclusion to recuperate from their three-month ordeal.

The diplomats, who left Tehran last weekend by using Canadian passports and forged Iranian visas, arrived at Dover Air Force Base in Delaware yesterday afternoon, according to U.S. officials.

State Department spokesman Hodding Carter said the American officials -- four men and two women -- would be kept in seclusion for several days, partly to protect them from "a ravaging horde of journalists" who might extract information that could endanger the estimated 50 hostages remaining at the U.S. Embassy in Tehran.

"There are extraordinarily sensitive matters involved," Carter said at his midday briefing.

There was not initial public announcement of the diplomats' 4:20 p.m. arrival in the United States on a flight from West Germany. American officials said the diplomats would remain temporarily at Dover Air Force Base where they are expected to rejoin their families today. A news conference has been scheduled Friday in Washington.

Their families, who initially expressed joy and relief at the diplomats' escape from Iran, spoke more cautiously yesterday, apparantly at the State Department's request. Asked when she expected to see her husband, Linda Anders, wife of consular official Robert G. Anders, replied, "I can't comment on what or where or if I'm on the way or not."

But there were also words of delight. Eva Schatz of Post Falls, Idaho -- whose grandson, Henry Lee Schatz, was among the six who escaped -- declared that she would have a big plate of her special fried chicken when he returned home. She said it was his favorite dish.

"I sure am glad he's back in the states," she added, "but I'm concerned about the other fellas left in Iran."

There were also congressional expressions of gratitude to Canada for its help in freeing the six Americans. A Senate resolution thanking the Canadian government was approved by voice vote with no objection and a similar resolution was approved unanimously in the House.

In addition to Anders and Schatz, the diplomats who escaped from Tehran ran are consular official Mark J. Lijek and his wife, Cora, a consular aide, as well as consular official Joseph D. Stafford and his wife, Kathleen, a consular assistant.

None of the six diplomatic officials has yet spoken publicly of the ordeal. Kim King, a seventh American who escaped from the U.S. Embassy during the Nov. 4 takeover and left Iran six days later on route to the United States, has recounted some of the events, however, in interviews with The Washington Post.

In an account published yesterday King, 27, an American tourist, described a 3 1/2-hour "nightmare," during which he he was barricaded in a section of the besieged U.S. compound with several of the diplomats who re turned to the United States yesterday. He said they escaped through a rear door to a deserted back alley during the takeover.

According to sketchy American and Canadian accounts, the six diplomats initially took refuge in a variety of friendly embassies after Nov. 4 assault on the U.S. compound in Tehran.Although officials declined to identify these embassies, one relative of a diplomat who escaped said she was told he was at the Swidish Embassy at one point.

Within a short time, the diplomats reportedly made their way secretly to the Canadian Embassy, which sheltered them in various Tehran residences under their control.

They left Iran with Canadian Ambassador Kenneth Taylor and three other members of his embassy staff last weekend, a time apparently chosen because of the Iranians' preoccupation with their presidential election.

The Senate Foreign Relations Committee resolution praised Taylor for his "courage and compassion." Canada has temporarily closed its embassy in Tehran, apparently as a precaution against possible reprisals for its assistance in the U.S. diplomats' escape.

Despite the plans for Friday news conference, U.S. officials made it clear yesterday they hoped to avoid excessive pulicity about the diplomats' escape. State Department spokesman Carter said the diplomats would be urged to "consider the implications of what they say" publicly about their ordeal, and to avoid statements that might jeopardize the safely of the 50 American hostages.

For the families, the past three months have been trying time, even though they were told the six diplomats were safe and not being held hostage.

Kathleen Stafford's mother, Mary Frank of Crossville, Tenn., said in a telephone interview yesterday that she had remained dubious and fearful despite State Department assurances. One official phoned her to confirm that the Staffords were not among the hostages at the embassy, she said, but another official later called to say they "were still in there."

"I came to believe they were still in there. No one would make it definite, one way or the other. It's been a horrible experience for our family and friends, but it's nice to know your friends care about you when you really need them. People have been calling from all over the country."