A group of Koreatown residents moved their redistricting battle to federal court Tuesday, accusing Los Angeles officials of illegally using race as the predominant factor to redraw City Council President Herb Wesson's district.

Weeks after new council district maps went into effect, five plaintiffs filed a lawsuit asserting that city leaders reworked political boundaries with the "explicit purpose" of increasing the percentage of African American voters in Wesson's district.

Wesson, who is black, represents all or part of Koreatown, West Adams, Mid-City, the Crenshaw Boulevard corridor and other nearby neighborhoods. Plaintiffs, all residents of his district, contend that the new boundaries sap Koreatown's political clout and discriminate against its residents.

"The city has diluted and negatively impacted the voting power of Koreatown residents by unnecessarily, unlawfully and unconstitutionally dividing their community into two separate districts," the lawsuit states.

The residents' lawyer, Hyongsoon Kim, said he wants a federal judge to bar the city from using the new districts in the March election. The lawsuit also calls for a court-supervised special master to redraw the lines.

Lawyers for the city had no comment.

The lawsuit comes about six months after activists demanded that Koreatown be moved from Wesson's district into one represented by Councilman Eric Garcetti. They argued that combining Koreatown with other parts of Garcetti's district —- Thai Town and Historic Filipinotown — would improve the chances of electing an Asian American candidate.

Villaraigosa and council members rejected those demands. After the maps were finalized, Matt Szabo, a top Villaraigosa deputy who handled redistricting, entered the campaign for Garcetti's council seat in the March election. (Garcetti is running for mayor.)

Tuesday's lawsuit marks the latest clash in an especially nasty once-a-decade redistricting process. Council members Jan Perry and Bernard C. Parks have accused Wesson of orchestrating changes that stripped their districts of economic assets. Wesson responded that he was only one of 15 council members.

Koreatown activists also attacked Wesson, accusing him of treating their neighborhood as "an ATM" — pulling out campaign contributions but failing to improve services.

Wesson dismissed the allegations, saying he had focused on bringing business and public improvements to the area. The issue resurfaced Tuesday, with the lawsuit's plaintiffs alleging that Koreatown lacks park space, community centers, senior housing and other services. The suit also claims the neighborhood lacks the "voting power or ability to ensure that the City Council responds to Koreatown's needs."

Wesson had no comment, a spokesman said. But earlier this month, the council president spoke at length about his effort to ensure that African Americans retain representation on the council.

Appearing before an audience at the Baptist Ministers Conference of Los Angeles, Wesson said he worked hard during the redistricting process to ensure that "a minimum of two of the council people will be black for the next 30 years."

"The most important asset that we have as people is to make sure we have a black vote or two on that council," Wesson said in the taped remarks. "And that was my priority."

Asked about those comments, Kim, the attorney for the Koreatown residents, said: "I think he's making our case for us."

david.zahniser@latimes.com