The nation's trade deficit narrowed sharply in September, as U.S. exports climbed by 14 per cent to a record $10.9 billion, the Commerce Department reported yesterday.

Analysts said that the lower deficit - it was $1.7 billion in September compared with $2.7 billion in August - did not represent an improvement in the nation's long-term picture but represents a step-up in shipments by exporters who were trying to beat the Oct. 1 dock strike.

The nation is expected to run a trade deficit of between $25 billion and $30 billion this year, with all of the imbalance due to an expected $45 billion of oil imports.

While oil imports account for more than the entire trade deficit, the trade surplus the nation runs in non-oil products has been shrinking steadily over the last three years, in large part because the major industrial economies in Europe and Japan have not been growing as fast as the U.S. economy.

That means demand abroad for U.S. products has not been growing nearly as fast as demand for imports in the United States.

Treasury Secretary W. Michael Blumenthal, who said earlier this year that he thought the huge trade deficit was only temporary, has said recently that he is more concerned than he was last spring. "Now we're no longer so certain we have a goid handle on it," Blumenthal said of the trade problem.

The swelling trade deficit - so far this year, U.S. citizens have spent $19.3 billion more abroad to buy goods than foreigners have spent in the U.S. - has contributed to the weakening dollar and has been used to strengthen the arguments of industries and unions who want to erect barriers to imports that threaten American jobs.

Furthermore, noted senior Commerce Department economist Maynard Comiez, when the nation runs big trade deficits for an extended period of time - buying goods from foreign, rather than domestic producers - it becomes harder to achieve goals such as reducing unemployment.

Comiez said that the deficit can be expected to swell again in October, in part because the East and Gulf coast dock strike will make trade more difficult and in part because exports that ordinarily would have been shipped in October were shipped in September.

The Commerce Department said that while the value of exports rose from $9.5 billion to $10.9 billion, imports increased from $12.2 billion to $12.6 billion.

During the first nine months of the year, exports totalled #90.6 billion compared with $85.2 billion for the first nine months of 1976, while imports totalled $109.9 billion compared with $88.3 billion for the first nine months of last year.

For all of 1976, the nation imported $5.7 billion more than it expected. In 1975, as the sharp U.S. recession reduced demand for foreign goods, the nation ran at trade surplus.

Commerce Department analysts said that there was a big jump in machinery exports last month, but that no particular type of machinery had a huge increase. There was also a surge of steel imports, a Commerce Department economist said. Nearly 20,000 U.S. steelworkers have been laid off since mid-summer, in part because of imports.

Oil imports, which had declined in July and August, climbed again in September. Oil imports will account for about 30 per cent of the nation's total imports. The oil bill will be about 10 times bigger this year than in 1972 before the Arab oil embargo.

Treasury Secretary Blumenthal is in the Middle East now to try to convince oil producers not to raise prices. Oil prices have risen more than fivefold since 1973.