Australian journalist Peter Greste says the decision by the Egyptian court to sentence his two colleagues to three years in prison was a political one.
Mr Greste, who was also sentenced in abstensia after being deported to Australia in February, said he was sickened and devastated by the verdict and sentence.
The verdict on Saturday, following a retrial, was issued against Al Jazeera TV journalists Mohamed Fahmy, Baher Mohamed and Mr Greste.
They were convicted of operating without a press license and broadcasting material harmful to Egypt.
Mr Greste told Nine to Noon he hoped the country's President, Abdel Fatah al-Sisi, would pardon him and his fellow journalists.
"We have to keep fighting. They're back in prison right now. They'll be in the middle of their second night at the moment. It means that even if we go through the appeals process and win that appeal they're going to be spending perhaps six months, maybe more, behind bars," Mr Greste said.
He said the prosecution had failed to prove the journalists had done anything wrong, because nothing was produced in court to substantiate the charges.
Mr Greste he was surprised by the verdict and sentence because there had been such "an eruption of outrage" when the journalists had first been convicted on the charges. He thought the court might have seen sense this time.
"The only conclusion we can come to is that this was a politically motivated decision. Now the courts have always insisted that they are politically independent but it is very difficult to understand, to explain, how they could have arrived at this conclusion."
Mr Greste said Mohamed Fahmy and Baher Mohamed would likely be in solitary confinement because that was the standard way of treating prisoners when they first arrived in jail.
He said no one had been able to get access to them yet.
"This is still going to be an incredibly tough experience for them, particularly because they're leaving behind families. In Baher's case, he has three young children including a one-year-old boy who celebrated his first birthday last Friday and of course Fahmy was married just a few weeks ago. He leaves his brand new wife behind. For all of them it is absolutely devastating.
"This is an injustice, and it's simply got to end."
The Egyptian foreign ministry has rejected international criticism over the sentencing of the three journalists. A ministry spokesperson said there were thousands of journalists working freely in Egypt and condemnation from other countries was unacceptable.
Human rights lawyer Amal Clooney, who represents one of the journalists, said campaigners would continue to press the Egyptian president to pardon them.