UPDATE 3-UK's Truss says she is determined to deliver N. Ireland bill in full

(Adds Sunak comments)

BELFAST, Aug 17 (Reuters) - Liz Truss, Britain's foreign minister and favourite to become prime minister next month, said on Wednesday she was determined to deliver the Northern Ireland Protocol bill in full, even if it faced time-consuming opposition in parliament.

The bill takes unilateral action -- effectively tearing up parts of the Brexit divorce deal -- to resolve a disagreement with the European Union over how to handle customs arrangements on goods travelling between Britain and Northern Ireland.

Truss acknowledged that the bill, which has faced strong criticism from political opponents in Britain and from the EU, would take time to pass through parliament's upper chamber, where the government does not have a majority.

With polls putting her far ahead of rival leadership rival Rishi Sunak, Truss is expected to be named prime minister on Sept. 5. But that seems unlikely to yield a significant change from current leader Boris Johnson when it comes to EU relations.

Truss on Tuesday accused the EU of a clear breach of the Brexit agreement, launching dispute resolution proceedings to try to gain access to the bloc's scientific research programmes.

Asked what guarantee she could offer that, if elected prime minister, she would not bow to those who oppose the planned legislation in the EU or in the United States, Truss said:

"I took on responsibility for negotiating the Northern Ireland protocol, and against a lot of advice in Whitehall and against the wishes of some of the people that you've mentioned - and I have been very clear with people like (U.S. House Speaker)Nancy Pelosi exactly what I think about this and exactly what we need to do - I have got on with delivering this."

Rishi Sunak, the trailing candidate and a former finance minister, said there was not much disagreement between him and Truss on the need to pass the legislation but that if elected, he would "of course" see if a negotiated outcome could be reached with the EU instead. (Reporting by Amanda Ferguson in Belfast, William James and Farouq Suleiman in London, editing by Elizabeth Piper and Toby Chopra)