Pillay also expressed concern at the highly restricted access to the Vanni region for aid agencies and impartial outside observers, including journalists and human rights monitors.
"The perilous situation of civilians after many months of fighting, multiple displacements and heavy rains and flooding is extremely worrying," Pillay said. "The lack of access for independent monitors, humanitarian workers and the media only adds to concerns that the situation may be even worse than we realize," she added.
The High Commissioner cited reports of forced recruitment, including of children, as well as the use of civilians as human shields by the Liberation Tigers of Tamil Eelam (LTTE). She also condemned the fact that safe zones promised by the Government have subsequently been subjected to bombardment leading to civilian casualties.
"People trying to flee the conflict areas are reported to have either been prevented from doing so, or to have been arbitrarily detained in special centres," she said. "It seems there may have been very grave breaches of human rights by both sides in the conflict, and it is imperative that we find out more about what exactly has been going on. It is also urgent that civilians in the north can find safe shelter, away from the fighting."
Pillay noted that along with the Secretary-General and other heads of UN agencies, she had already expressed her concerns directly to the Government of Sri Lanka. "We are all seriously alarmed by the situation," she said, "as are many of the NGOs and other organizations operating in Sri Lanka."
Pillay said the conflict had reached a critical stage: "While the Government has made military gains on one hand, the rule of law has been undermined on the other. The killing of the prominent newspaper editor Lasantha Wickrematunge earlier this month was the latest blow to the free expression of dissent in Sri Lanka. The searing article he wrote prophesying his own murder is an extraordinary indictment of a system corrupted by more than two decades of bloody internal conflict."
The High Commissioner observed there had not been any successful investigations or prosecutions of political killings, disappearances and other violations committed in recent years.
"It is the Government's duty to provide safety to all Sri Lanka's citizens, whatever their ethnic origin or political views," Pillay said. "That means not only protecting civilians during military operations in the north, but also ensuring space for journalists and human rights defenders to seek out the truth and expose abuses."
Pillay added that "a strenuous effort needs to be made to tackle the core problems that have fuelled this conflict for a quarter of a century, in order to bring peace and prosperity and restore fundamental rights and freedoms for all Sri Lankans in all parts of the country."