The Marine, &c., Broadcasting (Offences) Act 1967 (c. 41), shortened to Marine Broadcasting Offences Act or Marine Offences Act, was an act of the Parliament of the United Kingdom that came into force on 15 August 1967. It was subsequently amended by the Wireless Telegraphy Act 2006 and the Broadcasting Act 1990. Its purpose was to extend the powers of the Wireless Telegraphy Act 1949 (which was incorporated by this act), beyond the territorial land area and territorial waters of the UK to cover airspace and external bodies of water.

The act represented the UK's implementation of the 1965 "European Agreement for the Prevention of Broadcasts Transmitted from Stations outside National Territories" (sometimes referred to as the "Council of Europe Strasbourg Convention" or "Strasbourg Treaty").

At the time that the bill was introduced in Parliament in 1966, there were radio stations and proposals for television stations outside British licensing jurisdiction with signals aimed at Britain. These stations were anchored at sea but there were press reports of stations broadcasting from aircraft – Caroline TV, and from a ship – Radex TV.

The act was extended to the Channel Islands and the Isle of Man in September 1967. The act meant that the operation of offshore, pirate radio stations became illegal if they were operated or assisted by persons subject to UK law. It prohibited "carrying by water or air goods or persons to or from it" which made tendering illegal. Station operators thought they could continue if they were staffed, supplied and funded by non-British citizens, but this largely proved impractical.

In 1966, broadcasting in the UK was controlled by the British General Post Office, which had granted exclusive radio broadcasting licences to the British Broadcasting Corporation and television licences to the BBC and 16 regional Independent Television companies.

The power of the GPO covered letters delivered by the Royal Mail, newspapers, books and their printing presses, the encoding of messages on lines used to supply electricity; the electric telegraph, the electric telephone (which was originally deemed an electronic post office); the electric wireless telegraph and the electric wireless telephone which became known as "telephony" and later wireless broadcasting. In the 1920s the GPO had been circumvented by broadcasting from transmitters in countries close to British listeners. World War II terminated these broadcasts except for Radio Luxembourg.

In the 1950s a pressure group campaigned with the help of Winston Churchill to pass the Television Act 1954 that broke the BBC television monopoly by creating ITV. Some members wanted commercial competition to radio but were thwarted by a succession of governments.

By the 1960s, several companies formed in the hope that radio licences would be issued. Radio monopolies in adjoining nations had been broken by transmitters on ships in international waters. The first attempt to broadcast offshore to Britain was by CNBC, an English-language station from the same ship as Radio Veronica broadcasting in Dutch to the Netherlands. CNBC ended transmissions but press reports followed that GBLN, The Voice of Slough, would transmit from a ship with sponsored programming already booked and advertised by Herbert W. Armstrong. GBLN was followed by reports that GBOK was attempting to get on the air from another ship, both ships to be anchored off south-east England. Many in these early ventures were known to each other.