By Alastair Lawson BBC correspondent in Dhaka

The number of people killed by Royal Bengal tigers in southwest Bangladesh this year has already nearly equalled the total number of deaths last year, the Forestry Department has said.

Organised gangs kill Bengal tigers

As many as 22 people have been killed in tiger attacks in the Sundarban mangrove forest, the natural habitat of the world's largest tiger.

Figures released by the department also show that the numbers of the world's largest tiger continue to decline.

The department says that the most likely explanation for the rise in human casualties is the continuing encroachment on the tigers' territory.

The pressure for space in Bangladesh, one of the most densely populated countries in the world, is taking its toll both on the tiger and human populations.

Poaching threat

Wildlife experts say the real casualty rate among humans could even be higher than thought, because many people enter areas where tigers roam without informing the relevant authorities.

But the population of tigers continues to dwindle.

It is estimated that there are now only about 300 Royal Bengal tigers in Bangladesh, compared to 600 in the early 1990s.

Wildlife officials say attacks may be on the rise because tigers are more aware of the threat posed by poaching, which continues unabated despite a government commitment to punish offenders severely.

But the more plausible explanation is the continuing encroachment on tigers' territory by humans.

The victims of such attacks tend to be fishermen and honey collectors, who traditionally venture deeper into the forest.