An Al Jazeera journalist imprisoned in Egypt has thanked the international campaign to free him and his colleagues in a letter smuggled from prison.

Baher Mohamed is one of three Al Jazeera staff held by Egyptian authorities since December.

In the letter obtained by Al Jazeera on Monday, Mohamed spoke of his "gratitude and appreciation" for the way journalists around the world has responded to his detention.

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He said the efforts of journalists around the world in demanding his release made him confident about "the fight for freedom of expression".

The campaign to free Mohamed and his colleagues has enjoyed widespread social media participation, which he said had raised his spirits.

Along with Peter Greste and Mohammed Fahmy, the producer is accused of providing a platform to an outlawed group. Al Jazeera strongly rejects the charges and is demanding the release of all of its staff.

Abdullah Elshamy a journalist with Al Jazeera Arabic has been held since August without charge.

Source: Al Jazeera