BEIJING, JAN. 6 -- The Foreign Ministry today rejected any Chinese responsibility for the crippling of a Mexican student who alleged that he was beaten by Chinese civilians and mistreated by police.

Mexican Embassy officials here said they wanted a full investigation of the Dec. 30 incident in which Francisco Reyes, 34, fell from a factory roof and fractured his spinal column, leaving him partially paralyzed.

Reyes said he was pushed off the roof by an unidentified Chinese assailant and that the police, who said he was drunk, treated him like a criminal for seven hours before calling the embassy and taking him to a hospital.

The incident is a sensitive one, in part because China prides itself on good relations with developing nations and in part because more than 50 foreign students marched Monday to the Ministry for Public Security, which directs the police, to demand an investigation.

Mexican Embassy officials said they were still seeking an explanation for why Reyes, an art student who has been in China for more than 3 1/2 years, was not taken immediately to a hospital after his fall.

In a statement today, the embassy quoted a Chinese surgeon as saying that Reyes should have been operated on within six hours after his injury occurred. The five-page statement said Reyes will probably be an invalid for the rest of his life.

According to the statement, when Reyes recovered consciousness after his fall, "he cried and begged the police to call the Mexican Embassy, but instead, he says, he was mistreated by the officers, who thought he was a drunk and a criminal for a period of seven hours."

At a regular weekly news briefing, a Foreign Ministry spokesman expressed sympathy for Reyes but said investigaton showed the student had not been beaten before or after his fall and that his injury was self-inflicted.

"The important thing in this accident is that the Mexican student was injured after getting drunk," the spokesman said. It was the first comment by a high-level government spokesman on the inicident.

"I believe that on New Year's Eve, there are many similar accidents in your countries, as well, for some one to drink too much and get into trouble," the spokesman told reporters.

In interviews with foreign reporters, Reyes has insisted that an unidentified Chinese beat him up after he had spent an evening eating and drinking with three Chinese musicians in a hotel. He said that in desperation he fled onto the roof of an adjacent factory but the assailant pursued him.

"I got to the hospital and had spinal surgery, having one of my vertebrae completely twisted," Reyes is quoted as saying. "The result is that I am paralyzed from the thorax down, and probably, for the rest of my life."

"It could have happened to any foreigner in China," he added. "This, plus the stupid attitude of the police, are responsible for my difficult future as an invalid."

Security men at the factory where Reyes fell said no one was pursuing him at the time.

The Mexican Embassy statement noted that the main conflict between the student's account and that of the police and security men is on the question of how Reyes fell from the roof.