JERUSALEM, Jan 8 (Reuters) - Two Thai agricultural workers were wounded by a mortar shell fired by militants into an Israeli agricultural community close to the Gaza Strip border on Saturday, an Israeli official said.

One man suffered serious wounds and the second was in moderate condition, said Alon Shuster, head of the local municipal authority.

This is, of course, a very serious incident, one of the most severe we have had recently, it represents an escalation that appears to have reached a new height, Shuster said.

Militant group Islamic Jihad claimed responsibility for the attack. A spokesman said its operatives had launched six mortar shells into Israel.

The two men, who were ferried to hospital, were the first in Israel to be hurt by weapons fired from Gaza since December when a teenage girl was cut by flying glass after a rocket landed near a kindergarten at another agricultural community.

Violence has escalated in recent weeks along the frontier, though both Israel and Gaza's Islamist Hamas rulers say they are working to avoid a full-on confrontation.

On Friday an Israeli soldier was killed and four others were wounded from friendly fire during a clash with Palestinian militants. On Wednesday soldiers killed two Palestinians along the border as they attempted to cross into Israel, a military spokesman said. (Reporting by Ori Lewis in Jerusalem and Nidal al-Mughrabi in Gaza; Writing by Ori Lewis; Editing by Peter Graff)