London — International events are giving a greater sense of urgency to the seven-nation economic summit convening here today. In the Middle East, Saudi Arabian Air Force jets shot down two F-4 Phantom fighters over the Persian Gulf on Tuesday. In Latin America, Ecuador announced Monday that it is suspending debt payments to industrial country governments, four days after Bolivia said it is holding up payments to commercial banks.
Whether the summit talks will produce agreements for concrete action remains dubious.
Britain's Prime Minister Margaret Thatcher advised her countrymen last weekend in regard to the diplomatic spectacle: ''Blessed is he that expecteth nothing, and he shall not be disappointed.''
Most observers here share Mrs. Thatcher's assessment that the three-day gathering of the leaders of the United States, West Germany, France, Italy, Japan, Canada, and Britain is unlikely to produce solid decisions for dealing with such major issues as high interest rates, developing-country debts, increasing protectionism, and the security of oil supplies from the Mideast.
Allen Wallis, US undersecretary of state for economic affairs, notes that this summit will not provide ''startling news because the news deals with the present, but the summit deals with the future. The real test of the London summit's success will be reflected . . . in the months and years ahead when the United States and our summit partners try to implement domestically and internationally the policies sketched at London.''
Governments typically try to lower expectations of results before a summit. This summit is not considered even likely to produce any major controversy.
However, when the heads of government meet in the Music Room of Lancaster House, where Chopin played the piano for Queen Victoria in 1848, there will be some differences or nuances in positions:
* Interest rates. The four European nations will be pressing the US to reduce its budget deficits to bring down interest rates.
British Chancellor of the Exchequer Nigel Lawson said the US will need to reduce its deficit by more than the ''downpayment'' cuts now before Congress.
In an interview in the Financial Times, Mr. Lawson argued that the size of the deficit is making the capital markets pessimistic about future inflation, and thus lenders demand higher interest rates.
President Reagan assured Mrs. Thatcher Tuesday that his administration intends to seek further deficit cuts after the fall election.
In talks with the other finance ministers here, US Treasury Secretary Donald Regan may point to a new study by his department indicating little correlation between deficits and interest rates, and suggesting that other factors, such as tax changes favorable to investment, are more important causes of the high rates.
The summit pleas are not likely to have much impact on congressional budget action in this election year.
* Trade. Japan and the US will be pushing for a commitment to start a new round of multilateral trade negotiations to follow the so-called Tokyo Round. The goal would be not only to reduce trade barriers starting probably a few years from now, but also to restrain protectionist pressures in the meantime.
* Developing-country debt. In their briefings of the press, the European leaders have been emphasizing the need to deal with the ''bunching up'' in debt repayments the developing countries face between 1985 and 1987. Rescheduling of debts over the past two years has shoved major repayments into those future years.
The Europeans will suggest rescheduling several years of debt repayments at one time, instead of the present practice of one year at each negotiation. The US is not opposed to the basic concept. But it prefers to leave such matters to the commercial banks and their negotiations with the developing countries.
The bankers have been expecting to work out a longer-term rescheduling with Mexico next year. Mexico, though, is now in relatively good financial shape.
They may be hesitant to lengthen their leash for nations like Argentina, which has not yet reached a deal with the International Monetary Fund on conditions attached to a massive loan. And since the European governments prefer the country-by-country approach, they may also not want to give Argentina a special deal.
If there are any differences between the US and its allies on this issue, they are likely to be minor.
Meanwhile, seven Latin American debtor nations - Argentina, Brazil, Colombia, Ecuador, Mexico, Peru, and Venezuela - have sent a letter to the summiteers protesting the rise in US interest rates and calling for government-to-government discussion - as opposed to talks with the banks - on debt issues. The debtor nations are trying to present a united front in pressing for fresh approaches to solving the region's $350 billion foreign debt problem.
The seven summit leaders, in their final joint declaration, may say something about how the developing countries should encourage more foreign investment. That is one way to get more growth without adding to debts.