(CNN) -- Two senior Indian officials met with the Sri Lankan president Friday in Colombo to address the humanitarian crisis in the war-torn island nation.
A Sri Lanka army photo of what it says are refugees fleeing a rebel area.
Shiv Shankar Menon, the Indian foreign secretary and M.K. Narayanan, the national security adviser, met with President Mahinda Rajapaksa, according to A.M.J. Sadiq, a foreign ministry official in Sri Lanka.
He did not provide further details.
"The Indian message was just short of reading the riot act," a source told CNN.
Significant numbers of people have been killed or wounded in a Sri Lankan offensive against the faltering Tamil Tiger rebel movement, and thousands are trapped by the fighting, the United Nations said Wednesday.
"Given that the area has shrunk even further, the potential for further significant casualties still remains," the U.N. said in a statement.
The Sri Lankan army launched an operation against the Liberation Tigers of Tamil Elam in the country's northern area Monday, and a deadline for the rebels to surrender passed Tuesday.
Government troops say they have rescued 39,000 civilians trapped in the area, but tens of thousands more remain wedged on the island's northeastern coast.
The area remains controlled by the rebels, the U.S. State Department said Tuesday.
The Tigers have been fighting for an independent state in Sri Lanka's northeast since 1983.
As many as 70,000 people have been killed since the civil war began, and the group has been declared a terrorist organization by 32 countries, including the United States and the European Union.
Thousands of civilians remained threatened, Pranab Mukherjee, India's foreign affairs minister, said in a statement Thursday. He called for an end to hostilities in the area.
The U.N. High Commissioner for Refugees said it is helping the government in the regions of Vavuniya and Jaffna, with emergency shelters and distribution of aid. There are about 38 internally displaced persons sites and authorities are working to come up with more land and buildings for more displaced people.
"UNHCR remains deeply concerned about the estimated 50,000 people who are still trapped inside the conflict zone where fighting is intensifying," the organization said.
"We urge the government to exercise extreme caution in its military actions and calls upon the LTTE to allow displaced people to leave the area immediately," the UNHCR said.