Three Hungarians are thought to have been kidnapped in Syria, Prime Minister Viktor Orban's office said Tuesday.

"According to provisional information from the Hungarian anti-terrorism centre (TEK), three more Hungarian citizens have been kidnapped in Syria," a statement said. It gave no further details.

In late April the Hungarian government said that two Hungarians working in Syria had been snatched by unidentified gunmen in the south-east of the restive country. In late July the government said they were alive but still captive.

More than 23,000 people have been killed in violence in Syria since the outbreak of a revolt in March last year, the Britain-based Syrian Observatory for Human Rights said on Tuesday.