Federal officials are promising a more aggressive crackdown on unlicensed radio stations in Dorchester and Mattapan in a new approach signaled by a flurry of notice letters sent out by the Federal Communications Commission’s (FCC) Enforcement Bureau to three stations this month.

The letters were issued to individuals the commission says are affiliated with stations operating without a license on three FM bands: 101.3 FM, 87.7 FM, and 106.3 FM. According to the notices, if the radio stations do not cease operating immediately, the people named may be fined, have their radio equipment seized, or even be imprisoned.

The first notice, dated July 11, is addressed to Yvon Grand-Champ of Mattapan and states that Pastor Emmanuel R. Jules of the Revelation Pentecostal Holy Church identified Grand-Champ as the owner of the station. Contacted by phone, Jules said Grand-Champ was a friend who had set up the station— 106.3 FM— for use by local churches.

“Like on Sunday, if someone wanted to hear the service, they could” on the radio, Jules said, adding that he had not received the letter at the address where the station is located.

The other two notices were issued on July 13. One is addressed to Davina Mendes, who, the letter states, is an operator of the station at 87.7 FM and has an on-air program from 3 p.m. to 5 p.m. on weekdays; the other is to Talya Andrea Lantz, who, the letter states, is an operator at 101.3 FM and has a morning show.

Representatives from 87.7 FM did not immediately respond to request for comment. The station’s website indicates that a Diva Mendez runs a weekday program from 3 to 5 p.m.

As to 101.3 FM, the Reporter did not find any record of a Talya Andrea Lantz working there, but the station has a morning show called “Wake Up with Tayla Andre.” Contacted by phone, Andre declined to comment.

David Dombrowski, the FCC’s director for Region One, could not offer specific information on the three notices of unlicensed operations because they are considered open investigations. However, he said there is “more of a focus” on unlicensed operations under newly appointed FCC Chairman Ajit Pai.

“We have a Boston office up there and an agent, and we’ve brought in some additional agents to investigate these cases,” Dombrowski told the Reporter in a phone interview. He also referred the newspaper to a Mar. 1, 2016 enforcement advisory encouraging third parties such as landlords and advertisers not to support illicit radio stations.

“We need to identify operators and go after them,” Dombrowski said. “They try to hide behind the building operators, who may not be aware of the illegal stations, and then they just move.”

The Federal Communications Commission media relations office did not immediately return calls for comment, including requests for clarification on names and addresses.

This is not the first time that “pirate” radio outlets in the Boston area have faced aggressive enforcement.

In 2014, a popular, low-powered station — Touch 106.1 FM— was forced off the air after US Marshals seized broadcasting equipment from its Grove Hall-based studio. The raid followed several years of warnings and protests from the station’s operators. Last year, the FCC awarded a low-powered FM license to the city of Boston and the Boston Neighborhood Network (BNN) to create a community access station, which now operates at 102.9 FM.