Mr Brown has talked with the Israeli government and Palestinian Authority
Prime Minister Gordon Brown has offered British naval resources to help monitor events in the Gaza conflict and stop weapons being smuggled in.
He wants to help ensure protection and monitoring of the crossings into Gaza.
Mr Brown said: "We will do everything we can to prevent the arms trading at the root of the problems."
Israeli is to unilaterally halt offensive military activities in the Gaza Strip three weeks after operations began, Prime Minister Ehud Olmert said.
Mr Olmert's announcement came in a televised address following a late-night cabinet meeting.
He said Israel's operation in Gaza had fully achieved its aims, with Hamas badly damaged militarily and in terms of infrastructure.
Earlier, a Hamas spokesman said it would fight until its demands were met, including an Israeli withdrawal.
Mr Brown said he had been involved in talks with Mr Olmert and Palestinian Authority president Mahmoud Abbas.
"Germany, France and Great Britain have just sent a letter to Israel and Egypt to say they will do everything we can to prevent arms trafficking," he said.
"We're prepared to help move children, to take them out of the area so they can be treated elsewhere.
"We're also determined that we do everything in our power to deal with unexploded bombs so that people feel more secure in the Gaza area."
He promised that Britain would be increasing its humanitarian aid over the next five years.
Shadow defence secretary Liam Fox criticised the prime minister's offer of naval resources, saying he "must stop grandstanding and committing our already over-stretched forces to more and more missions while reducing their resources".
Mr Brown is considering an invitation to attend an international summit on Sunday in Egypt about the conflict.
Staged at the Red Sea resort of Sharm el Sheikh, it will be co-chaired by Egyptian President Hosni Mubarak and President Nicolas Sarkozy of France.
The Palestinian health ministry in Gaza has told the BBC that 1,193 people have been killed, including 410 children and 108 women, since the conflict began on 27 December.
There were 5,300 people wounded, including 1,600 children, the ministry said.
Thirteen Israelis, mostly soldiers, have been killed during the campaign.
Israel's military carried out 50 air strikes in Gaza overnight.
Palestinians say a tank shell hit a UN school in northern Gaza, killing at least two people sheltering there. Israel says it is checking the report.
The UN Relief and Works Agency (Unrwa) said Israel's actions in Gaza should be investigated as possible war crimes.
Mr Brown's announcement followed an agreement signed between the US and Israel on Friday.
The deal called for expanded intelligence co-operation to prevent Hamas smuggling weapons into the Gaza Strip.
Israel has accused Hamas of using tunnels between Gaza and Egypt to smuggle arms. The Egyptian government has said the tunnels are mainly used for food.