Some media outlets reported that the Monchegorsk was actually suspected of carrying arms destined for the Gaza Strip, which is controlled by Hamas. To quote the article by the Wall Street journal:
The Agence France-Presse media outlet (AFP) reported that the weapons were stored in excessively hot conditions leading to concerns about their stability. Indeed this may of course be the cause of the blasts. However, it does seem rather coincidental that the explosions took place less than two weeks after Greece and the Republic of Cyprus took steps to prevent the flotilla sailing to Gaza, in part since it has been two and a half years since the cargo was seized. Hamas’ political elite in Syria strongly condemned Greece’s actions as "inhuman". Both Greece and Cyprus are of course very closely linked.
Time will tell the cause of the blasts but a possible link with the Middle-East may become one line of enquiry, especially since Hamas’ political elite in Syria strongly condemned Greece’s actions as "inhuman", even though such expressions are to be expected. It should be noted that the connection between Hamas and the Gaza flotilla has been established by numerous sources such as the Iranian channel Press TV which reported collusion between the flotilla organisers and a leading member of the terror group, and Dutch Newspaper De Telegraaf.
Note: A similar article to the above by the same author was originally published at The Propagandist