(Reuters) Brazil’s state-run oil company Petroleo Brasileiro agreed to sell 90% of its natural gas pipeline unit to a group of investors led by Canada’s Brookfield Asset Management Inc for US$5.2b.

The investor group includes British Columbia’s pension fund and Chinese and Singaporean sovereign wealth funds CIC and GIC. The preliminary agreement will be submitted to the companies’ boards and the transaction is expected to close in late September, said the source.

Brazil’s state oil company, known as Petrobras, declined to comment on the matter, and Brookfield also declined to comment.

The deal will be the largest divestment so far in the heavily indebted oil company’s US$15bn asset sale plan.

Reuters reported on May 11 that Brookfield had entered exclusive talks to acquire Nova Transportadora do Sudeste SA, or NTS as the Petrobras subsidiary is informally known. The exclusivity period expired on Aug. 12.

The talks took longer than expected because the parties and their financial and legal advisers had to agree on terms of new contracts establishing the commercial relationship between Petrobras and NTS, according to the first source and two other people with direct knowledge of the matter. All three asked not to be identified because they are not authorized to discuss the matter publicly.

During the exclusive talks, the investor group led by Brookfield raised the stake it was offering to acquire in NTS to 90 percent from 82 percent.

The investment banking unit of Banco Santander Brasil SA (SANB11.SA) advised Petrobras on the deal.

The sale should give a boost to downsizing efforts at Petrobras, which hinge on divestments to cut the largest debt burden of any global oil firm, at around $US130b.

So far this year, Petrobras had sold US$3.9b in assets, of a total US$15.1b target for divestments expected by the end of this year.

NTS has nearly 1,560 miles (2,511 km) of pipelines in southeast Brazil.