PARIS, June 26--Soviet Foreign Minister V. M. Molotov, accompanied by three planeloads of aides, flow into Paris today for tomorrow's opening of Anglo-Russian-French discussions of European recovery, while the British were reported ready to demand a Sept. 1 deadline for the submission of a draft plan to the United States.

Foreign Secretary Ernest Bevin, bearing a mandate from the British cabinet to present Britain's views, was not due until tomorrow. An authoritative report from London said British and United States representatives there had reached "broad and general conclusions" on how U. S. Secretary of State George C. Marshall's proposal on European aid could best be approached.

William L. Clayton, U. S. Undersecretary of State for Economic Affairs, has been engaged in conferences with top British officials for several days.

Reports from both London and Moscow reported qualified optimism that the conference may be able to accomplish results. An Associated Press dispatch from Moscow said Soviet interest in all news of the Marshall plan was marked, and that this was a healthy sign.

The U. S. Ambassador to London, Lewis W. Douglas, told the American Chamber of Commerce in London, that Russia's attendance at the Paris three-power conference had raised "immeasurably more" confidence in its success, but coupled the statement with the warning obviously aimed at Moscow that "unilateral political acts" of interference in European countries must end.

Molotov was met at the airport by French Foreign Minister Georges Bidault and other French officials. After brief ceremonies he was whisked to the Soviet embassy where a guard slammed the heavy wooden gates behind him.

Less than two hours later Georgi Zarubin, Soviet ambassador to London, arrived by plane.