COLOMBO (AFP) -- The reclusive leader of Sri Lanka's Tamil Tigers is to deliver his annual policy address this week from a besieged jungle hideout that could soon be totally overrun by government troops.

With his northern fiefdom shrinking fast in the face of a massive onslaught, Velupillai Prabhakaran is expected to use Thursday's address to rally his forces for a do-or-die battle for survival.
The last 18 months have been disastrous for the Liberation Tigers of Tamil Eelam (LTTE), who want to carve out an ethnic homeland in the north and east of the Sinhalese-majority island.
The rebels were ejected from the east in July 2007 and lost their political chief in a government air raid, while much of their flotilla of ships used to smuggle in black market weapons has been reported sunk.
The LTTE's political capital of Kilinochchi appears to be on the brink of falling into government hands. The Tigers have lost control of the entire northwest coast, while the key northeastern coastal base of Mullaitivu is also being squeezed.
""He will vow to hit back. He might even say that they are pulling out so that the army will spread out thinly for him to attack them later,"" said Dharmalingam Sithadthan, a former Tamil guerrilla-turned-politician.
But a year ago Prabhakaran issued a similar threat against what he branded a ""genocidal"" government, only to see his northern mini-state shrink even further.
The hawkish and extremely confident Sri Lankan government pulled out of a Norwegian-brokered ceasefire in January. With his troops advancing, President Mahinda Rajapakse says he will accept nothing less from the LTTE than their surrender.
Analysts say Prabhakaran has been left with little room for maneuver.
""I think he may still have the capacity to carry out one or two big attacks, but that won't be enough to restore the military balance of power we see now,"" Sithadthan said.
Prabhakaran's speech is an annual event marking ""Heroes' week"", when the LTTE commemorates the estimated 22,000 Tamils -- many of them women and children -- who have died during the 36-year-long war.
The speech is usually pre-recorded in a jungle bunker somewhere in the northeast, and broadcast by the Voice of Tigers radio station. The station's previous headquarters was flattened by government jets a year ago.
The event also coincides with Prabhakaran's birthday -- he turns 54 on Wednesday -- although retired army brigadier general Vipul Boteju said the rotund rebel chief will have little to celebrate.
""He has to make a face-saving speech on Thursday,"" Boteju said.
""We will see the usual rhetoric about revenge, but his ability to deliver seems to be greatly diminished.""
The annual speech is also aimed at the Tamil diaspora in countries like Canada, Australia and Switzerland, who help keep the LTTE's coffers full.
But on the home front, he also has to raise morale among an estimated 200,000 Tamil civilians displaced by the government advance. Aid agencies say the humanitarian situation in the north is desperate.
Still, Prabhakaran and his hardened guerrilla force have managed to turn the tables on security forces in the past.
Military officials say the Tigers can still deploy large numbers of suicide bombers known as ""Black Tigers"".
Six months after he lost his northern stronghold of Jaffna to the army in December 1995, he overran an army base in the northeast, slaughtering over 1,000 soldiers and causing a dip in public support for the war in the south.
And in November 1999, the Tigers reversed military gains of 19 months in a matter of five days. That counter-attack helped push the Colombo government into a peace process.