Benitez, who played 58 times for Ecuador, scoring 24 goals, was the son of Ermen Benitez, one of his country's all-time leading goalscorers.
His Qatari club El Jaish, who signed Benitez only three weeks ago, had earlier reported his death on their website.
"Benitez... felt strong stomach pains, so he was taken in an emergency to a hospital where after a few hours he suffered cardiorespiratory failure which ended his life," the Ecuador Football Federation said in a statement on their website.
"The Ecuadorean Football Federation extends its deepest condolences to the relatives, parents, wife, children and friends of our goalscorer Christian Benitez."
El Jaish said: "The club would like to offer its sincere condolences to the family of the player.
"The player participated for the first time with the team during yesterday's match against Qatar Sports Club in the Sheikh Jassem Cup without complaining of any health problems.
"His sudden departure is a big shock for each member of the technical and administrative staff. He was a player that over the short period he was here was regarded for his high moral character."
The president of the Ecuadorian Football Federation, Luis Chiriboga Acosta, paid tribute to the attacker.
"This morning we woke feeling profound pain, a pain that all Ecuadorians share, after losing an extraordinary human being, a son, friend, husband and player," he said.
Chiriboga said the federation would charter a flight to return the deceased player's body to Ecuador along with his wife, adding that some Ecuador players, including Manchester United winger Antonio Valencia, had committed to helping with the process.
Chiriboga also announced that the main pitch at the national team's training ground would be named after Benitez.
Benitez joined El Jaish from Mexico's America for $15 million (£9.77m). He won the Mexican Clausura championship in May as their leading scorer with a tally of 30 in the 2012/13 season.
He had been linked with a return to England before moving to Qatar.
"America Football Club profoundly regrets the passing of one of the team's most recent idols and joins in the grief felt by the whole Benitez Betancourt family and Mexican, Ecuadorean and world football," the club said in a statement.
Benitez, nicknamed 'Chucho', came to prominence during the 2006 World Cup in Germany and was helping Ecuador in their bid to qualify for next year's finals in Brazil, making his last appearance against Peru in Lima in June.
Opponents in the qualifiers such as Argentina's Pablo Zabaleta and Radamel Falcao of Colombia sent Twitter messages expressing their sadness with Falcao writing "We'll miss you Chucho".
Benitez spent the 2009-10 season on loan at Birmingham City in the Premier League and the club said they would mark the player's death ahead of Saturday's Championship match against Watford at St Andrew's.
"The thoughts of all associated with the club are with Chucho's family and friends at this very sad time,” read a statement.
"The Ecuador international was an immensely popular character during his time at the club."
Fellow Ecuador international colleague Antonio Valencia paid tribute on Twitter.
“Brother why now. God is with you and your family,” the Manchester United winger tweeted in Spanish, before posting pictures of his friend.
His former Birmingham City team-mate Craig Gardner, now of Sunderland, also paid tribute.
"Can't believe Christian Benitez aka chucho has died," he tweeted. "Had the pleasure to play with him he was a top bloke. My thoughts go out to his family."
- Sports & Recreation
- Christian Benitez
- Ermen Benitez
- El Jaish