An ambassador from New Zealand said Sunday that he was "very concerned" about the safety of two kidnapped FOX News journalists, and urged their unknown kidnappers to "please release these men."

The ambassador, Peter Ridder, spoke outside the office of Palestinian Prime Minister Ismail Haniyeh in Gaza City shortly after the two men met. Ridder arrived in the area several days ago to lead a delegation working to free cameraman Olaf Wiig, 36, of New Zealand, who was seized Monday along with American correspondent Steve Centanni, 60, from their TV van near the Palestinian security services headquarters in Gaza City.

Earlier Sunday, Centanni's brother Ken appealed for his brother's safety.

"Please contact our family," Ken Centanni urged the kidnappers. "Let us know he is alive and unharmed." Centanni's comments, first shown on Fox television, were later aired on the Arab satellite TV station, Al-Jazeera.

Also Sunday, Ken LaCorte, a senior FOX News official, arrived in Gaza to follow up on efforts to release the journalists. He met with security officials and others, a local Fox reporter said.

More than two dozen foreigners have been abducted by Palestinian militants, usually in an attempt to settle personal scores, but almost all have been released within hours. This is the longest foreigners have been held. Security officials are especially concerned because all the militant groups have denied involvement and no demands have been put forth.

Ridder said he had no further information about the missing men. "Just like the family, we are very concerned about the safety and security of the hostages, and we are working together to try to secure their safe return."

Asked if he had a message for the abductors, the ambassador replied, "Please release these men."

Ridder spoke outside Haniyeh's office, where he had met earlier with the Palestinian prime minister. He said Haniyeh gave him his personal commitment that returning the men safely was a top priority.

A statement from Haniyeh's office said the government firmly opposed kidnapping journalists and promised to secure the journalists' release.