Google’s chief executive approved an agreement with Facebook at the heart of an antitrust lawsuit that 16 states and Puerto Rico have lodged against the search giant, according to a portion of the complaint revealed on Friday.

The lawsuit, led by the Texas attorney general, Ken Paxton, argues that Google has obtained and abused a monopoly over the network of technology used to deliver ads online.

When publishers started using an alternative system for selling their ad space, Google worked to undermine it by creating a similar system that it controlled, according to the lawsuit. The states argue that Google reached a deal with Facebook to have the social network join its effort in an effort to “kill” the publishers’ competing plan.

In the newly unredacted portion of the lawsuit, filed in federal court, the states said Sundar Pichai, the company’s chief executive since 2015, “also personally signed off on the terms of the deal.”

The newly visible parts of the lawsuit also include details of programs that the states say Google used to mislead buyers and sellers of ad space about the precise nature of the auctions they were participating in, allowing Google to make more money in the process.

A Google spokesman said the complaint was “still full of inaccuracies and lacks legal merit.”

“We sign hundreds of agreements every year that don’t require C.E.O. approval, and this was no different,” the spokesman said.

In another newly public portion, the states quote a February 2017 “Facebook document” that says that Google wanted to “kill” the competing system and that Facebook “baptizing their product will help significantly.”

At one point, Facebook employees working on the deal emailed Mark Zuckerberg, Facebook’s founder and chief executive, saying, “We’re nearly ready to sign and need your approval to move forward.” Mr. Zuckerberg’s name is still redacted from the lawsuit, but his title is not.

In a statement, a spokesman for Meta, Facebook’s parent company, said its deal with Google “and the similar agreements we have with other bidding platforms have helped to increase competition for ad placements.”

The antitrust lawsuit is one of several filed by government agencies against tech giants in the last two years. The Justice Department and a group of states have sued Google arguing that it has abused a monopoly over online search. This week, a judge said the Federal Trade Commission could move forward with a lawsuit against Facebook. Apple and Amazon are also facing antitrust inquiries.

The judge in the case has said Google has until next Friday to respond to the latest version of the lawsuit. Google plans to ask the judge to dismiss the case, its spokesman said.