JERUSALEM, Aug 3 (Reuters) - Israeli security forces set up roadblocks and launched a manhunt on Friday to find two men thought to have infiltrated from the Hamas-controlled Gaza Strip, although the pair may just be looking for work.

The high level response is an indication of how sensitive Israeli forces are about any possible incursions into the Jewish state, some of which are by militants planning attacks but others are by job and asylum seekers.

"The central command region is on high alert after two (Palestinians)... crossed into Israel from the southern Gaza Strip," police spokesman Micky Rosenfeld said.

The identity of the two men was not immediately known. Local media quoted security sources as saying the men did not appear to be planning an attack but might be looking for work.

Rosenfeld said the search had expanded from Sderot, an Israeli town close to the Gaza border, all the way north to Tel Aviv and beyond.

Israeli troops patrol the heavily fortified Gaza border with the Jewish state to try to stop infiltrations from the coastal strip, which Hamas seized from the control of Palestinian President Mahmoud Abbas's secular Fatah party in June.

In June 2006, an Israeli soldier was abducted and two others were killed when Palestinian militants tunnelled under the border fence from the southern Gaza Strip.

The captured soldier, Gilad Shalit, is still being held by Palestinian militants.

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