People have been urged to stay away from the cliff edge at Seaford and Birling Gap after a series of cliff falls.
The latest fall is believed to have happened overnight on Thursday night.
It follows several falls along the Sussex coast, including some at Birling Gap within the last week.
Newhaven Coastguard Barry Johnson said: "HM Coastguard are urging people to stay well away from cliff edges after multiple cliff falls throughout Sussex.
"The latest battering from huge waves and torrential rain has seen a large cliff fall at Seaford Head from the lower half of the cliff leaving a thin dangerously weak ledge at the top.
"Birling Gap has also experienced multiple cliff falls over the past week resulting in the beach being closed to the public.
"If you see any persons in difficulties on the coast do not attempt a self rescue. Dial 999 and ask for the coastguard who will task properly trained and equipped rescue personnel.
A spokesman for the national coastguard added: "In some parts of the country, conditions on the sea and along the coast are extremely treacherous with gale-force winds, high tides and heavy rain.
"Sending units to help people in these types of avoidable incidents will also put rescue teams at risk.
"If you do decide to venture out, check the prevailing weather conditions and make sure that you can handle them. If you are taking photos of the sea, take care, a great photo is not worth risking your life for. If in doubt, don’t go out.
"We are again advising the public to take great care when walking on cliff paths or along beaches, and take note of any warning signs in place.
"HM Coastguard’s advice is simple: don’t take risks. But if you do get into difficulty, or spot someone who might be in trouble, call 999 and ask for the coastguard."