An air carrier jet departing LAX Runway 25R suffered an NMAC with a Robinson helicopter at 800 to 1000 MSL while still over the airport. They had been advised the helo would remain below 1000 MSL and over the beach west of the airport and north of 25R.

Narrative

Lining up for takeoff on Runway 25R; LAX Tower informs us of low flying helicopter traffic; 'along the beach; below 1;000 feet; will remain north of 25R'. We see the traffic and acknowledge it; it is along the beach and no factor at the time. As we begin our takeoff roll; the helicopter makes a turn to the east; towards us. He is basically flying up the 25 Taxiways; at 800 to 1000 feet; we look out and see the Robinson 44 at our altitude and 250-350 feet lateral separation. It caused me alarm and I'm sure caused a level of alarm for our passengers. Possible security issue.....who are those guys? and how did they get so close to a commercial airliner in a critical phase of flight? Is their presence necessary? or was it just a 'wow' moment for the Robinson crew? wake turbulence hazard? any kind of southerly crosswind exposes the helicopter to potentially catastrophic wake hazard. I just would like an explanation as to why this helicopter was where it was. It was as close as I have come to another aircraft in flight and the feeling was uncomfortable. This comes from a former helicopter pilot.