The NFL players’ union emerged from a meeting Wednesday in Montreal with the league and officials of the World Anti-Doping Agency unsatisfied with how its questions about blood-testing for human growth hormone had been addressed.

The meeting came as the league and union attempt to work out the details of a program by which players would be blood-tested for HGH. No resolution was reached and the union continues to have questions about the reliability of the test and other issues, including health and safety of the players and athletes’ rights.

“We have an obligation as a union to protect the integrity of the game,” said George Atallah, the NFL Players Association’s assistant executive director of external affairs. “But we are disappointed in the lack of transparency related to the fundamental information required to begin HGH testing.”

Atallah said the union will agree to begin the testing “as soon as there is a fair, safe and reliable testing protocol that’s rooted in science.”

A program for HGH blood-testing “absolutely could be” in place by the opening week of the season as targeted, Atallah said, but he added, “We’re not going to let an artificial deadline drive this process.”

The league and union agreed earlier this month as part of their 10-year collective bargaining agreement for players to be blood-tested for HGH, with the goal of starting the testing the first week of the season. But first the testing details must be worked out.

“We gave them all the information,” David Howman, WADA’s director general, said in a telephone interview. “The scientists in the room were all satisfied. . . . It’s a very robust test and very conservatively applied.”

Howman said he was disappointed to hear later about the union’s reaction and he thinks NFL players are taking “a very strange approach” if they’re interested in clean competition.

Jeff Pash, the NFL’s executive vice president of labor who participated in Wednesday’s meeting, called it “a very comprehensive session” and added, “I thought the WADA people were very forthcoming in going through the research, the fact that there has never been a false positive.”

Pash said he believes “it can be worked out” to start the testing the opening week of the season.

“I certainly hope that’s the outcome [but] it’s not something that is totally in one party’s control,” Pash said.

A source on the players’ side said the union was “on board” with the HGH testing but hired its own researchers and wanted verification of the soundness of the WADA methods being endorsed by the NFL. Its concerns, the source said, include the reliability of the test, the amount of blood to be taken from players and the appeals process for players who test positive.

Pash said he thought the reliability issues were addressed by WADA during the meeting. The amount of blood to be taken from players is small enough that it shouldn’t be an issue, Pash said, adding that the two sides can work out the appeals process without WADA’s input.

Rep. Jim Matheson (D-Utah) wrote this week to both sides encouraging them to begin the testing program at the outset of the season. Other members of Congress previously urged the two sides to put the testing program into effect as soon as possible.