According to Focus Taiwan, Taiwan again came under pressure from the US on the pork issue in a report on foreign trade barriers issued by the United States Trade Representative's Office on Friday that insisted Taiwan respect maximum residue limits established for ractopamine - a leanness-enhancing veterinary drug prohibited in Taiwan - in pork.

Mr Chen had earlier told the media that he would not oppose lifting the ban on US pork as long as safety could be ensured. "If it is not safe, the ban cannot be lifted because of political considerations," he said.

In an interview with CNA on Monday, he reiterated his "safety first" policy, stressing that he will not allow any factors to affect his judgment about food safety, which he claimed is "the most important job of the Ministry of Health and Welfare."

He was then asked if his ministry could ensure the safety of American pork but the general public did not accept it, would he agree to the ban still being lifted?

He replied that he could understand the public's concern about food safety, and again repeated that "safety is my only consideration" on the issue.

In response to the US report on foreign trade barriers, the government said on Saturday that food safety and the rights of farmers will be major considerations in taking part in international trade deals.

The pork issue is seen as one of the most contentious between Washington and Taipei on the trade front and could affect whether Taiwan is able to participate in international trade deals that involve the US.

In the report, the USTR urged Taiwan to open its market fully to US beef and pork based on science, World Organization for Animal Health guidelines and the US's negligible risk status.

Taiwan has been reluctant to allow imports of US beef and pork that contain traces of ractopamine because of potential health hazards.

It relented on beef in 2012 after maximum residue limits for ractopamine in beef and pork were passed by a narrow margin by a United Nations food standards-setting body.

But Taiwan continues to ban ractopamine in pork, because of ongoing safety concerns about the drug and strong opposition from local hog farmers.

On 1 April, Presidential Office spokesman Alex Huang said the government will conduct risk assessments based on scientific evidence and international regulations.

In addition to mulling the idea of letting in US pork, the government also broached the idea of lifting import bans on Japanese food from areas affected by a nuclear meltdown in 2011.

Asked if his ministry has started to evaluate or set safety standards on "the safety of imports of food from Japan's nuclear-affected areas and pork from the US," Mr Chen said, "No. Everything remains as it is at this moment."