Hackers calling themselves the 'Iranian Cyber Army' have attacked the website of mainly Muslim neighbour Azerbaijan's state television station, the communications ministry said on Thursday.
In the overnight attack, the hackers replaced AzTV's homepage with the message: "Life is a game. Game over!"
The state airline AZAL was also hit by hackers calling themselves 'Cocaine Warriors from Persia'.
The attacks came a month after anti-Israeli hackers broke into the sites of several ministries and the governing party, leaving messages calling the Azerbaijani authorities "servants of the Jews".
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Azerbaijani media later reported that the attacks were believed to originate from Iran and that Azerbaijani hackers had responded by hitting several Iranian sites.
Tensions between Israeli ally Azerbaijan and the Islamic republic have risen in recent months, with Baku arresting several people with alleged links to Iran who the authorities said were planning to attack Israelis in the ex-Soviet state's capital.
AzTV reported the latest arrests on Tuesday, saying police had detained attack plotters with links to Iran's Revolutionary Guards and the Lebanese militant group Hezbollah.
Tehran has responded angrily, accusing Baku this month of collaborating with Israel's spy services and helping assassins who have killed Iranian nuclear scientists -- claims which Azerbaijan rejected as "absurd".
The uneasy relations between the neighbours are complicated by the presence of a huge ethnic Azeri minority in Iran, which far outnumbers Azerbaijan's own population of 9.2 million.