Montoya has signed a contract to join Nascar in 2007

The Colombian has been dropped from the McLaren race team after making public his deal to join Nascar in 2007.

But Dennis said: "Juan is contracted until the end of the year and, if we chose so, he will test and race again."

An imminent return is unlikely though - Pedro de la Rosa has been told he will do the next few races.

Despite originally announcing that the 30-year-old would sit out the rest of the season, Dennis insists it is "more than possible" that he will call on Montoya for future races.

A few races ago we had a conversation which was based on Juan Pablo's desire to stay with McLaren and Formula One Ron Dennis

"He is a contracted McLaren driver," said the team boss, "and he will stay that way until the end of his contract, unless there is some other commercial arrangement."

And Dennis dismissed suggestions that Montoya could join Nascar as early as next month, saying: "There's a conflict of sponsors, advertising campaigns - a whole raft of reasons why that is not a practical proposition."

Montoya, 30, fell out with McLaren after announcing his intention to join Nascar despite reportedly still being in talks with the team over a new contract for next season.

Dennis claimed that he and the winner of seven Grands Prix had resolved to look again at his contract situation at the end of the season during a recent meeting.

Dennis, left, says Montoya pledged to see out the season with McLaren

"A few races ago we had a conversation which was based on Juan Pablo's desire to stay with McLaren and Formula One," he said.

"We came to a very clear understanding that the best way to achieve that was to have the best results in the latter part of the season.

"The common objective was 'let's get the best out of the balance of the season', but that object was changed when he decided he would race in Nascar and the appropriate action was to let the whole thing cool off."

Dennis said Montoya's absence was unlikely to mean a promotion for McLaren's young British rookies Gary Paffett and Lewis Hamilton.

"It is highly unlikely," said Dennis. "Their programmes are well mapped and they didn't include racing a Grand Prix car this season."