Meta has been fined nearly €800 million by Brussels after regulators accused Facebook’s parent company of stifling competition by “tying” its free Marketplace services with the social network.

Margrethe Vestager, the EU’s outgoing competition chief, said on Thursday that by linking Facebook with its classified ads service Meta had “imposed unfair trading conditions” on other providers.

She added: “It did so to benefit its own service Facebook Marketplace, thereby giving it advantages that [others] could not match. This is illegal.”

Meta said it would appeal against the €797.72 million fine levied by regulators. “We built Marketplace in response to consumer demand—this decision ignores the market realities, and will only serve to protect incumbent marketplaces from competition.”