MILWAUKEE — State regulators in Minnesota have approved a $9 billion transaction that combines Wisconsin Energy Corp. and Integrys Energy Group Inc., leaving Illinois as the last state needed to approve the deal.

The Milwaukee utility holding company has now received approval from utility commissions in Wisconsin, Michigan and Minnesota as well as several federal agencies. The deal needs one more “yes” vote — in Illinois — to be completed.

The deal would create WEC Energy Group Inc., based in Milwaukee, with operations in four states and 4.4 million customers.

In its decision Friday, the Minnesota Public Utilities Commission declined Friday to require that Minnesota utility customers be awarded bill refunds or credits, as proposed by the state attorney general’s office.

Similar bill credits were sought for Wisconsin ratepayers by customer groups, but the Minnesota and Wisconsin agencies said the credits weren’t necessary.

The credits would have been within the range of the 3 percent to 5 percent in savings that the utilities have projected that customers could see as a result of combining the two companies.

Wisconsin Energy said it was not guaranteeing the savings would take place, and commissioners in Minnesota agreed with the utility that the merger was being undertaken based on growth opportunities rather than job cuts and savings.

In Illinois, Wisconsin Energy is expecting a decision to be made on June 24 by the Illinois Commerce Commission. During a recent investor call, company executives said the deal could be completed within days after the final state vote on the deal.