Workers are racing against imminent heavy rains to recover the last of the chemical barrels that were washed into a northeast China river last week, an emergency response official said Monday.

Heavy rains forecast to pound the flood-ravaged Jilin Province from late Tuesday to Friday could sweep the remaining barrels back into waterways, said a spokesman with the emergency response headquarters.

However, the provincial government's information office would not reveal how many of the 7,138 barrels had been retrieved on Monday.

More than 7,000 chemical barrels were swept into the Wende River, a tributary of the major Songhua River, after floods destroyed two chemical plant warehouses in Jilin City, Jilin Province on Wednesday.

By the end of Sunday, workers had recovered 6,387 barrels and located 684 others stuck in riverside corn fields or marshes.

A total of 3,662 barrels were filled with colorless and highly explosive chemicals -- mainly trimethyl chloro silicane and hexamethyl disilazane -- and 3,476 others were empty.

However, water quality tests showed the Songhua River, a major drinking source for millions in the region, had not been contaminated, said officials with the Jilin provincial government.

In a similar accident Friday, 1,500 sealed drums containing oil, resin and fertilizer sunk in floodwaters in the central China city of Wuhan, on the Yangtze River.

But all the drums had been safely recovered and the water quality of the Yangtze River was not affected.

Police have detained those responsible for the improper storage of the drums.