Shares in Monsanto soared nearly 8% after the seed biotechnology company raised its 2008 earnings forecast for the sixth time this year.

Monsanto increased its guidance for earnings per share for its 2008 fiscal year, which ran until the end of August, to $3.58-$3.60 per share. The estimate compared with the company's last guidance of $3.37 per share and investor expectations of $3.45 a share, according to a poll of analysts by Thomson Reuters.

Monsanto shares closed up 7.6% at $112.97 in New York, after touching $113.98 earlier.

The earnings increase reflected higher sales of seeds and weed killers including Round-up, Monsanto said. Gross profits at the US-based group's seeds and genomic division, the bigger of its two units, would reach $3.8bn, $100m more than previously forecast. Gross profits in corn alone would top $2bn for the first time.

"The fundamentals of agriculture and our businesses are strong and getting stronger," Terry Crews, the group's chief financial officer, said.

Monsanto viewed its improved fortunes as a spur to foreign growth, he added.

"We intend to continue to grow the footprint of our branded seeds and traits businesses globally," Crews said.