CAIRO — Egyptian President Mohammed Morsi offered nothing concrete to defuse the country’s worst political crisis in nearly two years in a nationally televised speech late Thursday, refusing to rescind a disputed constitution drafted by his allies or his decrees giving him near absolute powers.

A night after thousands of his supporters and opponents fought pitched battles outside his Cairo palace that left at least six dead and nearly 700 injured, he angrily accused some of the opposition protesters of serving remnants of the old regime. He vowed never to tolerate anyone working for the overthrow of his “legitimate” government.

Some among the thousands of opposition protesters gathered near his palace raised their shoes in contempt as they listened to him. Others broke into the iconic Arab Spring chant of “the people want to topple the regime.”

He also invited the opposition to a “comprehensive and productive” dialogue starting Saturday at his presidential palace, but offered no sign at all that he might offer them any meaningful concessions.

The opposition has already stated that it would not enter a dialogue with Morsi unless he first rescinds decrees giving him nearly unrestricted powers and shelves the constitution draft hurriedly adopted by his Islamist allies.

He said the referendum on the disputed charter, at the heart of the crisis, will go ahead as scheduled on Dec. 15 despite opposition demands to shelve the document.

He also refused to rescind his decrees of Nov.22 placing him above oversight of any kind, including by the courts, saying only that he was willing to annul one decree that gives him wide ranging powers to “protect” the nation and its revolution. He did not say how he would do that or give any other details.

Morsi, elected in June, was reading from prepared notes but frequently broke off to improvise. He wore a black tie in mourning for six people killed Wednesday in clashes.