Troops backed by helicopters have resumed heavy shelling of a Palestinian refugee camp in north Lebanon.
About 3,000 civilians are believed to be trapped in the camp
The official Lebanese news agency says one soldier was killed in clashes.
Militants in Nahr al-Bared camp north of Tripoli have been fighting the army since 20 May. Dozens of people on both sides have been killed.
Separately, reports say security forces have found three explosives-packed vehicles near the Syrian border. Two Syrians and an Iraqi were arrested.
The official Lebanese news agency said the vehicles had been prepared as car bombs.
There have been four explosions in the Beirut area over the past few weeks, killing one person and injuring many others. It is not known who is behind the attacks.
Government ministers have said the bombings were connected with the fighting in Nahr al-Bared camp and another camp in south Lebanon.
The Lebanese government has repeatedly demanded that the militants holed up in Nahr al-Bared camp, from the Fatah al-Islam group, surrender but most have refused to do so.
Split from Palestinian group Fatah al-Intifada in late 2006
Believed to have 150-200 armed men, based in Nahr al-Bared camp
Denies al-Qaeda links but says it endorses its ideas
Has links with Syrian intelligence, Lebanon says
Leader is Shaker al-Abssi
Humanitarian groups have voiced concern about worsening conditions. Heavy fighting means that supplies are not getting through to the estimated 3,000 refugees remaining in the camp which originally housed more than 30,000.
The International Committee of the Red Cross has warned that the refugees face a new threat from unexploded munitions, a problem which is also obstructing relief aid.
On Wednesday, a Lebanese military prosecutor charged 11 men from Fatah al-Islam with "acts of terrorism". In total 31 people have been charged in connection with the violence at Nahr al-Bared.
A small number of militants have surrendered to the mainstream Fatah Palestinian faction.
Earlier in the week, two Lebanese soldiers were killed in Ain al-Hilweh camp, in fighting with another militant group, raising fears that the violence was spreading. Ain al-Hilweh, on the outskirts of the southern city of Sidon, has been calm since then.
The Lebanese army has not entered the Nahr al-Bared camp.
There is a longstanding convention that the army does not enter Lebanon's 12 Palestinian refugee camps, leaving security inside to militant groups.
The violence is the worst internal fighting Lebanon has seen since the end of its civil war 17 years ago.
Lebanon is home to more than 350,000 Palestinian refugees, many of whom fled or were forced to leave their homes when Israel was created in 1948.