U.S. grain and soybean futures climbed on Tuesday, supported by a long backlog of corn and soybean export loadings at Brazilian ports and a broad rally in financial markets.

The gains in Chicago futures, which resumed trading after a three-day holiday weekend in the United States, pushed soybeans to their highest in more than a week and helped corn recover from a four-week low on Friday.

But ample global supplies, which are set to swell further as Brazil's ongoing soybean harvest rolls in, continued to cap prices U.S. exporters face a tough task in selling grain overseas.

Chicago Board of Trade's most-active soybean contract rose 0.8 percent to $8.79-3/4 a bushel by 1123 GMT, wheat added 1.2 percent to $4.62-3/4 a bushel and corn was up 1.1 percent at $3.62-1/2 a bushel.

Oil prices jumped as producers Russia, Saudi Arabia, Qatar and Venezuela met to discuss oversupply, and Chinese equities rallied on hopes of more stimulus measures, although oil gave back some gains as investors were disappointed by a potential output freeze agreed by the four producing countries.

In Brazil, the current line-up of ships to load soy and corn has grown to twice the level seen a year ago as excessive rains delayed loading and a weak currency boosts export sales.

"There is a bit of a recovery in prices in the overnight session," Stefan Vogel, head of agricultural commodity research at Rabobank, said. "There is some concern that beans are slow getting to port in Brazil. There are also a couple of macro factors today and crude oil was up sharply."

The port loading backlog in Brazil added to improving sentiments regarding U.S. soybean exports after better than expected weekly sales reported by the U.S. Department of Agriculture on Thursday.

Some traders expect China, the world's biggest soybean importer, to step up purchases following last week's Lunar New Year and a pre-holiday decline in imports during January.

Wheat prices were consolidating above last week's contract lows but the supply and demand outlook remained bearish, analysts said.

"I don't see wheat falling from here but I don't see it rallying much," Vogel said. "It's now a case of getting the Egyptian market running again and finding other outlets."

Egypt, the world's biggest wheat buyer, has canceled a string of tenders after weeks of confusion over its import terms left traders reluctant to bid.

In a sign the import wrangling is going beyond wheat, traders said on Monday that Egypt's agricultural quarantine authority had rejected four cargoes of U.S. soybeans due to higher than permitted levels of a fungus called ambrosia.