Figures from industry body Oil and Gas UK (OGUK) showed hydrocarbon releases - mainly gas - rose from 101 in 2018 to 125.
However, the number of releases classed as major actually fell from six to three.
It comes after the sector was warned about the number of releases by the Health and Safety Executive (HSE).
The safety body had said in 2018 that some releases had come "perilously close to disaster".
Last year, the largest gas release was reported to be on Perenco's Lancelot platform in the southern North Sea which amounted to 26,500kg (58,422lbs).
OGUK's health, safety and environment director Trevor Stapleton said the industry had to take any hydrocarbon release "very seriously".
He said: "The UK offshore oil and gas industry's work to improve safety performance is delivering in many areas - but we must continue our relentless focus on safe operations in every aspect.
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