Pressure mounted on Libyan strongman Moammar Gaddafi on Sunday, as the head of Britain’s military called for more extensive NATO airstrikes and prosecutors in the International Criminal Court announced that senior Libyan government officials were cooperating in a war crimes investigation.

After a week in which NATO forces significantly increased their bombardment of Tripoli, Gen. David Richards said Sunday that he wanted to widen the range of targets that NATO could hit to tighten pressure on Gad­dafi to abandon his 41-year rule.

“NATO is not attacking infrastructure targets in Libya,” Richards told London’s Sunday Telegraph newspaper. “But if we want to increase the pressure on Gaddafi’s regime then we need to give serious consideration to increasing the range of targets we can hit.”

Richards said he was concerned that the situation would reach a stalemate without increased NATO strikes. Attacking infrastructure targets, rather than purely military targets as has been done so far, could increase the risk of civilian casualties, although Richards said that “if any risk is posed to Libya’s civilian population then we do not hit the target.”

Libya’s deputy foreign minister, Khaled Kaim, on Sunday called Richards’s comments “provocative.”

“They are attacking infrastructure whether it is civilian or military,” Kaim said. “We don’t take it as a positive sign,” he said, adding that officials had raised objections with a UN envoy in the country Sunday and with the UN Security Council.

NATO jets could be heard above Tripoli on Sunday afternoon.

Also Sunday, prosecutors from the International Criminal Court announced that they had received phone calls from senior Libyan officials offering to provide information to an investigation of war crimes committed by the Libyan government, the Associated Press reported, suggesting that some Libyans are hedging their bets in the expectation of Gaddafi’s eventual downfall. Prosecutors did not divulge which officials had been cooperating or what they said.

The International Criminal Court has said that it will announce arrest warrants Monday against three senior Libyan officials for crimes against humanity. It has not specified which officials would be charged, but Gaddafi is presumably among the three.