Manmohan Singh wants Pakistan to take action against Mumbai attackers
Indian Prime Minister Manmohan Singh has ruled out talks with Pakistan until it takes "credible steps" to bring the Mumbai attackers to justice.
India blames Pakistan-based militant group Lashkar-e-Taiba for the November 2008 attacks which left 174 people dead, including nine gunmen.
On Monday, India and Pakistan's PMs met at a nuclear security summit in the US.
Pakistani PM Yousuf Raza Gilani spoke to Mr Singh at a reception hosted by US President Barack Obama.
A Pakistani embassy spokesman said it was "not a formal meeting".
Prime Minister Singh said he had briefly met Mr Gilani twice in Washington, but that the two leaders had only exchanged pleasantries and that "there was no serious discussion".
"We would like Pakistan to at least bring all of these perpetrators of these horrible crimes to book and do so effectively," news agency Reuters quoted Mr Singh telling reporters.
"That's the minimum that we expect from Pakistan. If Pakistan does that, we will be very happy to begin talking once again about all of these issues," he added.
On Monday, Mr Gilani had said that Pakistan had taken action against Lashkar-e-Taiba, but India needed to provide more evidence.
Mr Singh said he did not see "any need to provide any additional evidence to Prime Minister Gilani on this".
The meeting between the two prime ministers came a day after Mr Singh told President Obama that Pakistan's government lacked the will to punish those responsible for the Mumbai attacks.
Late last year, Pakistan charged seven people in connection with the attacks.
They include the suspected mastermind Zaki-ur-Rehman Lakhvi, who is allegedly the leader of the Pakistan-based militant group Lashkar-e-Taiba.
India put peace talks on hold after the attacks, suggesting what it calls "state elements" in Pakistan were involved. Pakistan and Lashkar-e-Taiba have denied any involvement.
In February, Pakistan and India held their first formal talks since the 2008 attacks and agreed to "remain in touch".