A forthcoming U.S. report that shows child labour has risen in the West African cocoa sector is to be reviewed independently after Ivory Coast and Ghana objected to the methodology, the U.S. Labor Department said on Friday.

The Labor Department, which sponsored the report, did not say whether the review by a group of independent experts would delay publication of the report, expected later this month.

A draft of the report that was reviewed by Reuters found child labour on cocoa farms in Ivory Coast and Ghana, the world's top producers, had risen over the past decade despite promises by chocolate makers and cocoa traders to reduce it.

The Ivorian and Ghanaian governments objected to aspects of the methodology, including how comparisons were made between data collected for the current report and data from a previous report in 2015 that turned out to be flawed.

The latest report is the third in a series called for by an agreement between the cocoa industry and U.S. lawmakers first struck in 2001. The report's surveys were conducted in 2018 and 2019 by NORC, a research organisation at the University Chicago.

In a statement to Reuters, a spokesperson for the U.S. Labor Department said it believed the researchers had made every effort to consult the two governments but that it had accepted the governments' requests for an independent review as a matter of "good faith".

"Our expectation is that NORC will take into proper consideration the findings of the Experts Group, and as necessary and where possible, make any appropriate adjustments to the report," the statement said.

"We trust that the two governments will respect the findings of this independent Experts Group," it added. It did not say who would be in the group.

The Labor Department did not say how long the review would take.

Officials in Ivory Coast and Ghana had no immediate comment. A NORC spokesperson did not immediately respond to a request for comment.

(Reporting by Aaron Ross; Additional reporting by Ange Aboa in Abidjan and Christian Akorlie in Accra; Editing by Susan Fenton)