NEW YORK (Reuters) - A mysterious, maple syrup-like odour that has periodically wafted over New York City since October 2005 has been linked to New Jersey fragrance processing plants, New York Mayor Michael Bloomberg said on Thursday.

Fragrance and food additive factories in nearby New Jersey where fenugreek seeds are processed are the "probable source" of the odour, Bloomberg told a news conference at City Hall.

The odour has attracted media attention and hundreds of complaints from city residents.

"Given the evidence, I think it's safe to say that the 'Great Maple Syrup Mystery' has finally been solved," Bloomberg said.

The city had assured residents that the odour was not harmful, but it was not able to explain its source until now.

The mystery was solved after city agencies matched complaints by their geographic location against information about winds and atmospheric conditions.

"The health department confirmed that the odour does not pose a health risk, but I am pleased to know that our ... smelling sleuths got to the bottom of this mystery," Bloomberg said.

(Reporting by Edith Honan; Editing by Eric Beech)