Commissioner Stuart M. Statler, who has been an outspoken critic of his conservative colleagues on the Consumer Product Safety Commission, has sent a letter of resignation to President Reagan protesting that administration budget cuts have undermined the agency's effectiveness.

"We are at a point right now where we can't effectively target new trouble spots or correct many of those already threatening," Statler said in his letter. "As a result, more Americans will be maimed and charred and killed before we can even begin to seek solutions." He said he will leave the commission June 1.

The resignation of Statler, appointed in 1979 by President Jimmy Carter, comes at a time when both he and his chief opponent -- Commissioner Terrence M. Scanlon -- have been accused of using commission staff for personal business.

Sources close to the commission indicate that Statler and Scanlon largely blame each other for their problems.

Scanlon, who chaired the commission for about a year while his nomination was pending, was accused of using government employes for personal typing and antiabortion activities.

An investigation last year by the General Accounting Office found no proof to support the charges, but members of Congress have called for further investigation. Pending confirmation, Scanlon has stepped down as chairman, but continues to serve on the commission.

Meanwhile, on March 19, after a story appeared in The Washington Times, several members of Congress asked the GAO to look into charges that Statler used agency lawyers to do research on whether his wife, Jean, could claim back pay for two years of work as a political appointee at the Environmental Protection Agency.

The allegations against Statler were based on a Feb. 14, 1986, signed statement from George E. Hill, a commission attorney who said that in early 1985 he and "others" spent 50 to 70 hours on a memorandum dealing with "whether a GS14 incumbent was entitled to back pay because his predecessor in that position was an SES Senior Executive Service employe and had received SES compensation for performing the same duties that the GS14 incumbent was performing."

Hill, a former U.S. attorney and state judge in Michigan, said in the signed statement that during his research he learned that the employe in question was Statler's wife. He concluded that the employe was not entitled to back pay.

According to Hill's statement, Statler called him after receiving his legal memorandum and requested more information. When it was not provided the same day, Hill said, "Mr. Statler telephoned me the next day and told me with vehemence that a commission employe should comply with a commissioner's request immediately. He demanded that the material be delivered to him before noon."

Statler provides a different account of the events. He said in an interview that he "asked a casual question" about his wife's situation to an employe in the personnel office, implying that he wanted to address the question to the Office of Personnel Management.

" She said she'd like to check it out. Later she got back to me and said she'd like to bounce it off the general counsel's office," Statler said.

He says that eventually he got a three-page memo from Hill, called to thank him and asked for some of the backup material. But Statler denied making a second call criticizing Hill for the delay.

Informed of Statler's comment, Hill said, "I stand by my statement."

Asked about rumors that political opponents of Statler's may have persuaded him to make his charges, Hill, a Democrat, said, "I was neither coerced nor induced, and I volunteered the statement because I think people in public life -- liberals or conservatives -- should have integrity, honesty and truthfulness."

The GAO has agreed to look into Hill's allegations, as well as private allegations that Statler used commission employes for personal business.

Statler, meanwhile, says he believes he has been targeted by conservatives because of his strong pro-consumer stance. The request for the GAO investigation was signed by conservative Republican Sens. Jesse Helms and John P. East of North Carolina, Steve Symms and James A. McClure of Idaho and Chic Hecht of Nevada.

Statler, also a Republican, said, "It's not enough to be a Republican any more . . . . Being a good Republican these days means you have to click your heals and subscribe . . . to a right-wing ideology."

Statler, complaining that the commission is not doing its job, said, "There is a real reluctance to enforce the laws, to deal with unreasonable risk of injury to consumers . . . . There will be more needless tragedies, and American families will be victims of this current unwillingness to regulate."

He blames the administration's current "philosophy of deregulation . . . In the health and safety area, that's been interpreted to mean you don't make waves for industry. We're a watchdog agency that's becoming a lap dog. Industry says heel and we heel."

Scanlon denied Statler's charges: "I think the commission has an adequate budget to protect the public, and I think we're doing a good job. We're enforcing the law. We're probably looking at fewer things than we were 10 years ago, but I think we're better focused today."

Statler said he believes the commission's future is "kind of bleak. Not that my staying would have made much difference. But at least there was someone who would stand up [for the consumer].