Swiss agricultural chemicals group Syngenta is about to launch the sale of its vegetable seeds business as it seeks to raise money for a share buyback, according to sources familiar with the matter.

The company, whose main business is making pesticides, is under pressure to offer tangible rewards to shareholders after it turned its back on a $47 billion bid from Monsanto. It said this month it plans to buy back more than $2 billion worth of stock to boost investor returns.

It has asked JP Morgan to organize the sale of the vegetable seeds business and it could fetch around $2 billion, the sources said. The unit had sales of $663 million last year, representing about 4 percent of group sales.

Information packages on the unit, which includes a strong tomato-seeds business, are expected to be sent to prospective buyers as early as this month and tentative bids are likely to be due before Christmas, they added.

Syngenta and JP Morgan declined to comment.

The vegetable seeds business is likely to appeal to other large agricultural chemicals groups, some of who may however shy away due to antitrust concerns, the sources said.

Smaller players seeking to expand their product range may also bid, they added.

In the seeds business, Syngenta competes with big groups like DuPont, Dow, Bayer and Monsanto. Smaller peers include companies like Israel's Adama, majority-owned by ChemChina, Australia's Nufarm , Germany's KWS Saat, France's Vilmorin and Limagrain.

Some smaller firms may tie up for a potential bid, due to the size of the asset, one of the sources said.

KWS and Limagrain have partnered in the past, merging their North American corn seeds businesses in 2000 to form the third-largest player in corn seeds in the United States, AgReliant.

KWS, a supplier of conventionally bred seeds, said in June that it would look at vegetable seed assets if they were put for sale by Syngenta or Monsanto.

While the vegetable seeds unit represents a relatively small proportion of Syngenta's revenue, it is the most profitable of its seeds businesses. It has gross profit margins of well above 60 percent compared with about 45 percent for all seeds last year.

But the need to raise cash for the share buyback has persuaded Syngenta to part with it, according to the sources.

Valuation multiples in vegetable seeds are "quite easily" in the 3-6 times sales range, Syngenta's finance chief said earlier this month, although industry bankers said the business was more likely to fetch a multiple of around 3.

Syngenta has not released a figure for earnings before interest, taxes, depreciation and amortization (EBITDA) for the business. But bankers said they estimate it having a margin of roughly 20 percent - which would imply an annual EBITDA of around $130 million.

"I can imagine the unit fetching a multiple of more than 15 (times EBITDA) in a sale," one of the sources said.