German Foreign Minister Guido Westerwelle arrived in Cairo on Wednesday for talks with Egypt's interim government and backers of ousted president Mohammed Morsi.

A spokesman said the visit was aimed at encouraging the country to return to the path of democracy and had been closely coordinated with EU foreign policy chief Catherine Ashton, who visited Cairo this week.

EU foreign affairs head Catherine Ashton who has just completed her second trip this month to Egypt is ready to return if she can help resolve the country's crisis, her spokesman said Wednesday.

"Ashton (is) willing to return to Egypt in order to help facilitate moves towards democratic transition," Michael Mann said in a tweeted message.

Two leading U.S. senators said they have been asked by President Barack Obama to travel to Egypt to urge the country's military to hold new elections, U.S. media reported Wednesday.

Republican senators Lindsey Graham and John McCain, seen as leading legislative voices on U.S. foreign policy and security matters, told reporters that they plan to travel next week to Cairo.

U.S. Defense Secretary Chuck Hagel on Tuesday again called on Egypt's military to show restraint in the wake of often deadly protests.

Hagel spoke to General Abdel Fattah al-Sisi by telephone after EU foreign policy chief Catherine Ashton paid a first-of-a-kind visit to ousted president Mohammed Morsi.

An Egyptian soldier was shot dead in the Sinai Peninsula on Tuesday, raising the 36-hour toll of security forces in the area to five, local sources said.

Medical and security sources said armed men had attacked a military building in Al-Arish, the regional capital of North Sinai, killing the soldier.

The European Union is playing a mediation role in helping to restore civilian rule in Egypt where it is an important source of foreign aid, a senior EU official said Tuesday.

"We have already played a very important role as facilitator in Egypt and we will continue to do that," said Michael Mann, spokesman for EU foreign affairs head Catherine Ashton.

France's foreign minister demanded Tuesday that Egypt's ousted president Mohammed Morsi be freed, describing the political crisis as "very critical" after bloody unrest in Cairo.

"We condemn the violence... We call for dialogue and for the release of president Morsi," Laurent Fabius told reporters.

EU foreign policy chief Catherine Ashton met Egypt's ousted president on Tuesday, saying he was "well," but the country's political crisis seemed no closer to resolution despite her efforts.

Neither the interim government nor supporters of deposed President Mohammed Morsi showed any indication that they had shifted their positions after talks with Ashton, who left Cairo on Tuesday.

At least 15 people were killed on Monday night in a brawl between Cairo street vendors over space, including 13 who were burned to death, a security source told Agence France Presse.

The source said two people died of gunshot and stab wounds in an initial brawl in central Cairo, and 13 more were killed after the shop they took refuge in was set on fire.

A group of Egyptian NGOs called on Monday for the interior minister to be dismissed over the deaths of at least 72 people at a Cairo protest.

The groups also urged the Muslim Brotherhood, which has led protests calling for the reinstatement of ousted president Mohammed Morsi, to reject violence.