UPDATE 12pm: The FTSE is 20 points higher while other key European markets have jumped 1.3% on news Portugal has succeeded in raising £1bn in a bonds auction, easing concerns over the country's need for an EU bailout.
The FTSE advanced 40 points in early trading on Tuesday as investors were buoyed by news of US tax cuts, but European debt fears were keeping a lid on sentiment ahead of the Irish budget.
The FTSE 100 advanced 0.67% or 38.68 points to 5,771.51 as investors responded positively to news Ireland has agreed to a bailout.
The FTSE 100 dropped 0.49% or 28.19 points to 5,768.68 in early morning trading, as fears of lower demand from China dragged down mining stocks.
Positive earnings reports from some of the FTSE 100 top players have boosted the index this morning.
The FTSE 100 opened positively in a week set to be dominated by a slew of US economic and political news.
The index of 100 leading shares was down a third of a percent just after opening, as the markets await figures for UK growth.
The FTSE 100 rose 0.9% to 5,791.10 in early morning trading as a weaker US dollar provided support for mining stocks.
The FTSE 100 had a slow start to the week, down 0.32% or 18.43 points to 5,684.94, following mixed sessions in Asia and the US.
The UK index of 100 leading shares was up in early trading, lifted by rises in all the major global markets.