The Group of Five finance ministers agreed at a private dinner meeting Wednesday night that Japan will get increased voting power in the World Bank reflecting its growing economic status, sources said yesterday.

This will pave the way for a general increase in the World Bank's capital at the 1979 joint annual meeting of the Bank and International Monetary Fund, which starts early in October in Belgrade.

The Gourp of Five ministers -- who meet privately from time to time -- included U.S. Treasury Secretary W. Michael Blumenthal, British Chancellor of the Exchequer Denis Healey, West German Finance Minister Hans Matthoefer, and Japanese Central Bank chairm,an Teiichiro Morinaga, who represented Japanese Finance Minister Ippei Kaneko.

The Group of Five also discussed the problem of an IMF loan to Turkey, and sources indicated that a compromise on that touchy issue may be worked out.

On the question of the voting power in the World Bank, Japan for some time has pushed hard for recognition of its enlarging economic staus in the world. It has ranked fifth in The World Bank behind France, with the United States, the United Kingdom, and West Germany first, second and third, respectively.

Cirrently, Japan has 15,900 votes in the bank affairs, compared with 17,862 to which France is entitled if it fully pays in its share of a special capital increase voted two years ago.

The Group of Five ministers agreed on a compromise that keeps France in the fourth position, but with its margin over Japan substantially narrowed.

To the suggestiong that the issue and changes seemed small, the insider explained: It's a matter of national prestige and pride. Besides, it foreshadows trends that are still to come."

With this problem settled, it is expected that the annual meeting will go forward with an approximate doubling of the bank's general capital from something just under $40 billion in current dollar terms to about $80 billion.

The government of Turkey had rejected the tough conditions demanded of it by the IMF for the priviege of receiving a loan of about $500 million.

President Carter, West German Chancellor Heimut Schmidt, French President Valery Giscard d'Estaing, and Prime Minister James Callaghan of Britain had made a political commitment at their January meeting in Guadeloupe to get about $1 billion in help to the troubled government of Turkish Prime Minister Bulent Ecevit.

But the Ecevit government complained that the conditons laid down by the IMF were too tough, and refused a stand-by credit installement of $300 million proferred by the IMF.

The Gourp of Five, all of whom had met with the IMF staff and other Finance Ministers yesterday in the framework of the Interim Committee, decided to try to get the IMF and the Turks to continue their negotiations. "The IMF will probably find some way and the Turks would do well to talk to each other reasonably and see each other's problems, and I think they will," said a high official.

Once the IMF loan is agreed to, sources said, private banks will be willing to reschedule some $2.5 billion in loans due to be repaid this year, as well as advance new credits.

Turkish complaints about the IMF condtions probably are exaggerated. "The British, Italians and the Mexicans all screamed about IMF conditions before getting their stand-bys," said one financial man "and then afterward they all said it was the greatest thihg that ever happened to them."