The severely split reform movement in the United Mine Workers Union officially broke apart today as union secretary-treasurer Harry Patrick announced he will challenge incumbent Arnold Miller for the union presidency.

Charging that Miller had "surrounded himself with yes men, paper pushers and payrollers," Patrick said he reluctantly decided to challenge his former ally because he could no longer stand by to see the union "torn apart by bitterness" and inept leadership.

"Arnold Miller took office with the best of intentions," he said. "BUt time after time, in crisis after crisis, he has been reluctant to make the tough decisions that much be made in that office. He has turned away from problems, has been an absentee president, and then when problems have mushroomed out of control he has looked for other people to blame them on."

The long-anticipated announcement was expected to divide the ranks of the union reformers who just four years ago overthrew the regime of W. A. (Tony) Boyle, now serving a life sentence for being convicted of ordering the murder of union insurgent Joseph (Jock) Yablonski.

The chief beneficiary of the split will be Lee Roy Patterson, a union district official from Madisonville, Ky., and a former Boyle loyalist. Long the leaser of anti-Miller factions, Paterson has the support of union vice president Mike Trbovish , who shared the reform ticket four years ago with Patrick and Miller.

"Naturally Patrick's going to help me because people who vote for me don't like either one of them," Patterson said.

Patrick, a 46-year-old former miner from Fairmont, W. Va., said he decided to run because if he did not, "the members of this union would be faced with a choice between a man who will not lead and a man who wants to lead the UMW back to the dark days."

Patrick's announcement sets up what promises to be a bitter, if somewhat confusing, battle for control of the 277,000-member union, one that will be watched closely by both entrenched union machines and would be reformers in other unions. The election is scheduled for June, six months before the coal workers' contract with operators expires.

Miller could not be reached for comment today. But in an interview Tuesday he accused Patrick of using "Hitler-like big lie tactics," and "forgetting where he came from." As for Patterson, he said, "He would be just like Boyle. He'd offer no new programs, nothing for the membership. He'd want to run the union in a dictatorial way."

Patrick's entry into the race comes at a time when Miller has alienated most other top union officials as well as many of the young reformers who helped put him in office.

Patrick, a leader in the mineworkers' reform movement since 1969 and a pallbearer at Yablonski's funeral, was urged by many of these persons to enter the race. But he had difficulty piecing together a slate to run with and securing support of other union leaders.

This was evident in his failure to announce a candidate on his slate for secretary-treasurer. Named his vice presidential running mate was Mike Tamton, president of the UMW district in western Canada and a former mine mechanic. "I feel we have been made the laughing stock of the labor movement," Tamton said of the Miller regime.

Patrick belongs to a large coal mining family. A miner until 1972, Patrick until recently had been one of Miller's most vocal defenders against attacks by Trbovich and other hostile elements on the union's executive board. But he gradually became disillusioned with Miller, particularly his handling of wildcat strikes that shut down the coal fields for several weeks last summer.

Referring to the wildcat strikes he said, "I'm not going to disappear from my office without leaving a forwarding address or phone number while 80,000 miners are out on strike for a month before I try to do something about court injunctions. I'm not going to run away from confrontations with miners."

The Miller-Patrick alliance first began to show severe strains in late summer before the union's national convention. Miller, however, survived a series of challenges at the often stormy convention. His reputation and his relationship with Patrick were soiled but most of his powers remained intact.When he returned to Washington, the union president fired two of his longtime aides whom he had suspected of having pro-Patrick leanings.

Later, Miller instituted a series of tough office rules like restricting travel and telephone use. Patrick complained that the rule changes made him a virtual prisoner in his office, which he said was extremely uncomfortable because Miller had turned the heat off.

When Patrick charged Miller with turning on his friends and aiding his enemies. Miller said in an interview, "I don't know I had any friends in his office."