Sete Gibernau parts company with his bike in Barcelona

But Italian team-mate Loris Capirossi, also involved in the six-rider crash in Barcelona, will compete at Assen.

Gibernau, who is 11th in the overall standings, had a further brain scan on Wednesday as well as surgery to fix a minor fracture to his left collarbone.

According to Doctor Xavier Mir, the Spaniard will need three to five weeks recovery before he could race again.

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"The operation went well," said Dr Mir. "We removed the plate covering the old injury to Sete Gibernau's left collarbone and repaired the new fracture by applying a new titanium plate."

Gibernau's place in the Dutch MotoGP has been taken by 26-year-old German Alex Hoffman, who has been riding a non-works Ducati for the Pramac d'Antin team.

Capirossi was kept in hospital overnight and then returned to his base in Monte Carlo with his physiotherapist.

"That was a big crash but luckily I got off quite lightly," he said. "I received a nasty blow to the chest, which is still bothering me.

"I'm not yet 100% fit but the important thing is to get back on the bike as soon as possible and see how it goes.

"I'm going to Assen with even more fighting spirit than usual."

American Nicky Hayden, riding for Honda, leads the championship ahead of second-placed Capirossi.