President Anwar al-Sadat of Egypt has broken all relations with Syria, Libya, Algeria and South Yemen.
He has ordered their diplomats to leave Egypt within 24 hours and recalled his envoys from the countries.
The move is in retaliation to the four nations and the Palestinian Liberation Organisation signing the Declaration of Tripoli.
The document is an official pledge to "freeze" relations with the Egyptian Government.
Hostilities have been growing between Egypt and her former allies in the region after Mr Sadat visited Israel last month and became the first Arab leader to recognise the state.
The agreement in Tripoli is said to have formed a unified military front against Egypt which includes sanctions against any Egyptian company or individual doing business with Israel.
The coalition is also considering moving the headquarters of the Arab League from Cairo.
It called on all Arab states to give full financial, political and military assistance to Syria as the main confrontation state and it condemned Mr Sadat's visit to Israel as "high treason".
Egypt is now expected to expel an estimated 200 diplomats with the Syrians leaving first.
It is not yet known if Egypt will take any action against Iraq which walked out on the talks in Tripoli.
Iraqi president Ahmad Hasan al-Bakr refused to agree to the declaration because the remit was too vague and he wanted tougher sanctions against Egypt.
The Egyptian move is seen as a damper on the forthcoming visit to the Middle East by the US Secretary of State Cyrus Vance.
Mr Vance will be seeking Arab support for Mr Sadat's peace initiative and his plans for preliminary talks on the subject in Cairo.
The following September the Egyptian and Israeli leaders met with American president Jimmy Carter and signed the Camp David Peace Accords.
That same year President Sadat and Israeli Prime Minister Menachem Begin jointly won the Nobel Peace Prize.
But when the peace treaty between the two countries was signed in March 1979 Egypt was condemned by the other Arab nations and excluded from the Arab League.
In October 1981 Present Sadat was assassinated by Islamic militants angered by his deal with Israel.
Since then Egypt has regained favour with Arab states and become pivotal to diplomacy throughout the conflict between Israel and the Palestinians.