The Quartet consists of the United Nations, the United States, the European Union, and the Russian Federation. It deals with the Middle East situation.
Statements of the Quartet are issued as press releases by the country or organization that hosts the meeting. This can make it hard to find their press releases unless the UN is the host. Try searching the web if you don’t know the host.
The earliest mention we have found of the Quartet date is from late 2001.
A/56/642 – S/2001/1100
“Russia, together with the American co-sponsors of the peace process, with the European Union, with the United Nations and within the framework of the quartet of international intermediaries and other concerned parties, will spare no effort to overcome the explosive spiral of recent developments and to revert the process to a political settlement.”
“The “Quartet” encouraged their representatives in the field to continue working together to help the Israelis and the Palestinians find a way to resolve the current crisis in their relations.”
Press Briefing 20/11/2001
“In the statement -– the full text of which is available upstairs — the Secretary-General also reiterated his readiness to work closely with Israel and the Palestinians, with the United States and other members of the so-called “Quartet”, which includes the European Union and the Russian Federation, as well as with Egypt and Jordan and other interested Member States, to ensure that peace and stability are attained in the region.”
(Although this says the full text was available in the Press Office, we have not found this.)