Fresh rebellions broke out in opposite corners of Iran today, prompting Islamic revolutionary leader Ayatollah Ruhollah Khomeini to appeal to the Sunni Moslem ethnic minorities in the border regions to vote Friday and Saturday with the Shiite Moslem Majority of the country for the establishment of an Islamic republic.

The Shiite leader spoke fo the "disturbing news from Gonbad, Zahedan and Ardebil"-towns repectively in the Turkoman region in the northeast, Baluchistan in the southeast and Azerbaijan in the northwest.

Meanwhile, the government moved to counteract signs that the referndum turnout would be light by extending the voting period from one to two days. It was also learned that five members of former prime minister Shahpour Bakhtiar's Cabinet have been arrested.

Fighting has been going on in Gonbad-e Kavus for three days and reportedly has calmed down today, but Khomeini's statement about the other two towns was the first public news of outbreaks there. Telephone links with the towns seemed to be cut and it could not be determined exactly what was going on in those localities separated by theShiite-populated Iranian heartland.

Political groups representing most of Iran's ethnic minorities have called for a boycott of the national referendum on the Islamic republic.

Not only is the explosive mixture of ethnic differences and religious sectarianism causing growing concern for the young revolutionary authorities, but rival attempts to organize forces of law and order behind competing political strains are raising the specter of warlordism in a country where the police and armed forces are totally disorganized.

The army has been placed on a three-day state of alert for the referendum, but there was skepticism that it could do much in its present condition. Officials have said that army forces have gone into action against Turkoman rebels in Gondad and surrounding towns.

Khomeini attributed the latest troubles variously to "the clergy . . . depriving our Sunni brothers of their rights," to "inspiration from America" and to elements pretending to be leftists.

In every case where the details of regional conflicts have become known, the fighting originated in minor incidents that would probably have been quickly settled in normal times. But tensions apparently are so high and the police and gendarmerie so weak that the smallest problem can turn a whole province into separatist rebellion.

Meanwhile, the government displayed concern today that the national turnout in the referendummay be embarrassingly light. In announcing the extension of the voting period, the Cabinet spokesman, Vice Premier Amir-Entezam, told a press conference that he expects only about 12 million people to vote out of a total on the voting rolls of nearly 19 million.

It was not clear whether the number he gave for the electorate includes 16 and 17-year-olds, who have been extended the right to vote, officially because of the important role the young people played in overthrowing the rule of Shah Mohammad Reza Pahlavi. But lowering the voting age also increased the pool of potential referendum voters by more than a million.

In an election appeal to his "brothers" of various nationalities, Bazargan added a minority not usually mentioned in lists of the major groups-"my Bakthiari brothers." They are a relatively small Shiite warrior tribe of about 850,000 in south-central Iran.

Former prime minister Bakhtiar, the last head of government before the Islamic revolution triumphed two months ago, is one of the three chiefs of the Bakhtiaris, and there have been persistent rumors that he is in hiding among his tribesmen.

A report came from Isfahan today of posters appearing in the town signed by an uncle of Bakhtiar saying that anyone who wished to arrest his nephew must "talk with Bakhtiars first."

Over the weekend, the Tehran offices of both the BBC and Agence France-Presse received tapes of a statement by Bakhtiar, now generally accepted here as genuine, denoucing the new leadership as "a dictatorship with energy," opoosing the referendum and saying he would not vote for the Islamic republic. Among other reasons, he said that no one knows what it is.

Stories appeared in the two main afternoon newspapers today that five members of his Cabinet had been arrested. Two of the former ministers' wives confirmed that the men were rounded up on Monday. The ministers of foreign affairs, information, health, industry and postal services reportedly were picked up.

It was also reported that the government had quietly released 304 political prisoners deemed to be innocent of crimes under the shad.

When reporters asked Entezam why groups opposing the Islamic republic have been unable to get time on state radio and television to air their views, the vice premier answered, "There are a number of things that are not under our control. Two of my most important interviews were not shown on television, and I don't know why."

Questioned about this and about failure to carry many of Prime Minister Medhi Bazargan's most important speeches in which he has been taking a distinctly different approach from Khomeini, radio TV chief Sadegh Ghotzadeh said there is no obligation to carry all of the prime minister's statements. "Are all of Carter's speeches broadcast?" he asked.

Ghotbzadeh said that Bazargan had made "a big mistake" by complaining publicly about what he called the "parallel government" of the revolutionary Committees. He said that the Bazargan the committees to keep the country going.

[In Washington, it was announced that Iranian citizens in the United States who are over 16 can vote in the referndum from 9 a.m. to 7 p.m. Friday and Saturday in all five consulates-located in New York, at the embassy in Washington, and in San Francisco, Chicago and Houston-by showing their passports.]