Speaking in Cairo on Monday, head of the journalists' union Jalal Arif said the president had informed him of the decision in a telephone call earlier the same day.
The proposed change to the law is to be put to the National Assembly later this week, although the decision could not be immediately confirmed.
Journalists have been campaigning for the move to protect freedom of expression, as Western allies - especially the United States - step up calls for political and democratic reforms.
Diplomatic pressure also increased after the convictions of several reporters sent to prison for "defamation".
In a speech read for the president by Information Minister Safwat al-Sharif at the opening of the conference, Mubarak emphasised his unswerving support for press freedoms and criticised foreign pressure for reforms in the Middle East.
"I reject any interference limiting the independence of the Egyptian press or freedom of expression."
But Mubarak also criticised "foreign powers ... working to impose a precise type of reforms ... supposing that the lack or the slowness of reforms in the Middle East made it a dangerous region".
He also warned against any "attempt to impose reforms on Arab countries ... without prior consultation. Our cooperation with the outside world in the application of our reform plans should preserve our Arab identity."
The reference was apparently to a US master plan for the democratisation and economic liberalisation of the Middle East, which is riling Arab governments who fear direct meddling in their affairs.