A spokesperson told PNGIndustryNews.net the security breach was at the Tamadigi area EPC 5A camp 4, operated by pipeline contractor Spiecapag in Papua New Guinea's Southern Highlands.
"Work has been temporarily suspended in the Tamadigi area and there is some damage to camp facilities," the Exxon spokesperson said.
"Planning is underway to resume work."
Few details were shed on the fatality.
"We understand there has been a death of a man working for a contractor on the project," the spokesperson said.
"The cause and whether it was related to the breach of security is not yet known.
"We understand there was an initial media report linking gunfire to his death. Information we have indicates this was not the case.
"We are deeply saddened by the loss of life and an investigation as to the cause and nature of the incident is underway."
Late last week, PNG blog LNG Watch reported the worker was shot by mobile squad police officers who were called to the site after a dispute between landowners and police broke out.
Landowners had allegedly petitioned the project after they claimed their only source of water had been contaminated by pipeline construction and the local community demanded an alternative water supply.
More than 700km of pipe, including about 407km of offshore pipeline, is required to transport the gas from the Southern Highlands and Western provinces to the proposed two-train, 6.6 million tonne per annum LNG plant near the Gulf of Papua.
First exports are expected in 2014.
There was another project fatality in February, which occurred at the Komo airfield construction site.