A longtime ally of Mayor de Blasio Monday blasted his administration as “incompetent and immoral” for not giving minority- and women-owned firms more city contracts.

Black Institute CEO Bertha Lewis dropped the bombshell before testifying at a City Council hearing.

Lewis, the former head of ACORN who campaigned for de Blasio in 2013, complained City Hall is moving at a glacial pace on boosting minority contracts.

“This administration is incompetent and immoral when it comes to MWBE [minority- and women-owned business enterprise] issues,” Lewis said.

“Minorities elected him! What is happening here is disgusting and appalling.”

City Comptroller Scott Stringer gave the city a D report card for minority hiring last year, with 5.3 percent of the city’s $13.8 billion procurement budget going to MWBE firms, up from 3.8 percent the year prior that included the end of Mike Bloomberg’s tenure.

“We’re putting our money where our mouth is,” De Blasio counsel Maya Wiley said.

“We have awarded $1.6 billion in contracts to M/WBEs, certified a record-breaking number of M/WBE businesses with the City,” Wiley said.