The Indonesian arm of e-commerce firm Shopee has admitted violating anti-monopoly rules and agreed to change some of its operations, Indonesia's antitrust agency, or KPPU, said on Wednesday.

The KPPU said in May it was monitoring the Indonesian units of e-commerce giants Shopee and Lazada over allegations of anti-competitive behaviour.

PT Shopee International Indonesia and logistics company PT Nusantara Ekspres Kilat had admitted to violating Indonesia's anti-monopoly and anti-competitive provisions, the KPPU said in a statement.

"The admission will be included in the behaviour change integrity pact which will be signed by both reported parties at the next hearing," it said.

The next hearing is set for July 2.

Shopee, owned by Southeast Asian technology firm Sea Limited, and Lazada, a subsidiary of China's Alibaba Group, are key e-commerce players in the region.

Shopee Indonesia's head of public affairs Radynal Nataprawira said the firm had proposed changing its user interface to suit local regulations during a hearing with the KPPU last week.

"Shopee is always committed to complying with all applicable regulations and laws in the Republic of Indonesia in conducting our business operations," Radynal said in a statement.

The KPPU accused Shopee's Indonesia operation in late May of anti-competitive behaviour by favouring certain delivery services, including PT Nusantara Ekspres Kilat.

The KPPU is also investigating Lazada's PT Ecart Webportal Indonesia.