Luis Suárez, the Uruguay striker banned for four months for biting Giorgio Chiellini, claimed in his defence to Fifa that the shocking act was not deliberate and he simply lost his balance and fell on to the Italian player with his teeth.

In a defence that makes the “dog ate my homework” excuse look plausible, Suárez wrote to Fifa’s disciplinary panel saying the incident was an accident. “In no way it happened how you have described, as a bite or intent to bite,” the forward wrote in Spanish, in a letter dated 25 June and revealed on Saturday.

“After the impact … I lost my balance, making my body unstable and falling on top of my opponent,” he said in his submission to the panel, which met on Wednesday, a day after Uruguay had beaten Italy 1-0 in a decisive group-stage match. “At that moment I hit my face against the player, leaving a small bruise on my cheek and a strong pain in my teeth,” the Liverpool striker said.

The player could be seen holding his teeth following the incident with Chiellini but the seven-strong panel dismissed Suárez’s argument after studying the incident from 34 camera angles. The bite was “deliberate, intentional and without provocation”, the ruling read. “He bit the player with the intention of wounding him or at least of destabilising him.”

Suárez was banned for nine Uruguay matches and four months from all football, including domestic Premier League games for Liverpool. He was also fined £66,000. The Uruguayan Football Association said on Thursday it would appeal against the ruling and have a further seven days to prepare the paperwork.

Fifa’s ruling confirmed the referee, Marco Rodríguez of Mexico, acknowledged in his match report that he missed Suárez’s bite. So did his two assistants and the fourth official. “I haven’t seen the incident because the ball was in another sector of the pitch,” Rodríguez admitted in the 11-page document.

The ban was more severe because it was not the first time the player had been involved in a biting incident. Suárez has received bans for biting opponents while playing for Ajax and Liverpool.

Another reason for the unprecedented punishment was the Uruguayan showed no repentance for the incident and previous bans had not changed his behaviour. “At no time did the player show any kind of remorse or admit to any violation of Fifa rules and therefore showed no awareness of having committed any infraction,” the Fifa document read. The document showed a proposal for a six-game ban was considered but rejected as insufficient. “The minimum punishment was not sufficient to have the necessary dissuasive effect. Previous bans did not have an effect.”

Suárez, who is back in Uruguay, where he met the country’s president and waved to fans from his balcony, has received plenty of backing from within Latin America and tweeted on Saturday to acknowledge the support: “Hi all, I write this post to give thanks to the outpouring of support and love I am receiving. Both myself and my family really appreciate it. Thank you very much for being by my side and I want to support all my colleagues selected for the match against Colombia.”

Luis Suarez (@luis16suarez) Hola a todos, escribo este mensaje para dar las gracias a todas las muestras de apoyo y cariño que estoy (cont) http://t.co/2uo0LXaqs2

Uruguay were due to face Colombia in the World Cup’s knockout round late on Saturday.