The number of Syrian refugees going into Turkey has grown in recent days, officials said, most of them frightened by a government assault to drive rebels from the Baba Amr neighbourhood of Homs.
Amos arrived in Turkey earlier on Friday, after a trip to Syria where she said she had witnessed significant devastation in Baba Amr and wanted to know what happened to residents who had endured a 26-day military siege. Rebels withdrew a week ago.
Amos was due to meet with Foreign Minister Ahmet Davutoglu at around 1100 GMT in Ankara, a ministry official said. A UN official said she was expected to make a statement at Ankara airport at 1200 GMT, before flying to Istanbul.
Some 12,000 Syrians are registered at several camps set up in Turkey's southern province of Hatay, including about 800 who crossed during the past week, according to the Foreign Ministry.
Two Syrian generals, a colonel and a sergeant were among 234 people who arrived in Hatay's Reyhanli district on Friday, a Foreign Ministry official told Reuters. Similar numbers were now crossing over on a daily basis, he said.
Ankara has turned against former friend President Bashar al-Assad over his brutal crackdown of protesters, and fears that there could be massacres in Syrian towns and cities that are centres of opposition to his rule.
The United Nations is readying food stocks for 1.5 million people in Syria as part of a 90-day, $105 million emergency plan to help civilians deprived of basic supplies after nearly a year of conflict.
The UN World Food Programme (WFP) said it had distributed some food supplies in Syria through local aid agencies, but it had not reached people in the areas worst hit by the violence.
The UN estimates more than 7,500 civilians have died in the crackdown.