Leader of Opposition in Rajya Sabha Arun Jaitley said that international diplomacy though important should not be followed at the cost of Parliamentary accountability.
"This is a bad precedent. I hope the government will take note of this in future," he added.
He said that Singh's absence has forced cabinet ministers and even Ministers of State to answer questions ideally meant for the prime minister.
"Result of this Prime Minister's absence is that when it comes to issues of government accountability, its standard is falling," Jaitley said.
Jaitley expresses disappointment at PM's failure to address parliament regarding the Copenhagen Summit.
Environment Minister Jairam Ramesh addressed parliament in the absence of PM with respect to the summit.
Prime Minister Manmohan Singh had been on foreign tours ever since the winter session of parliament began on November 19.