He is widely believed to be the latest in a series of kidnappings of western journalists by Palestinian militant groups. Unlike previous abductions he was not released within a fortnight, however.
The 44-year-old's plight was today highlighted by groups of Palestinian journalists and media sector workers, who demonstrated with banners demanding his release in towns in both the West Bank and the Gaza Strip.
On Thursday the British government's consul general in Jerusalem met with Palestinian prime minister Ismael Haniyeh to discuss the situation.
The Palestinian government has condemned the unconfirmed kidnapping and insisted it continues to try hard to secure Mr Johnston's release.
But observers fear Mr Haniyeh's ability to influence the situation may be limited by his need to avoid inflaming volatile tensions within Palestinian politics, following a period of significant instability during the last few months.
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