AJDABIYA, Libya — Military forces loyal to Col. Muammar el-Qaddafi cranked up military and psychological pressure on the rebels on Monday, offering amnesty to those who surrendered their weapons but bombing a strategic linchpin in the east and invading a rebel-held town in the west.

Government warplanes launched fresh strikes against this anxious town on the doorstep of the opposition capital, Benghazi, and almost abreast of a highway crucial to recapturing the eastern border and encircling the rebels with heavy armor and artillery.

Residents of Zuwarah, an isolated city near the Tunisian border in the west, told Reuters that the pro-Qaddafi forces that surrounded them three days before had taken control. “Zuwarah is in their hands now,” said one resident, Tarek Abdallah. “They control it and there is no sign of the rebels. They are now in the center — the army and the tanks.”

The developments came against a background of quickening diplomatic debate over possible outside help for the Libyan rebels, who have made increasingly anxious pleas for intervention that have, so far, produced none. The United Nations Security Council took up the contentious question of a no-flight zone on Monday, but no decision was reached.