The FTSE 100 index is seen falling on Tuesday, tracking weakness overnight in Asia, after ratings agency Standard & Poor's warned it may downgrade 15 euro zone countries, including top-rated Germany and France, if EU leaders fail to agree on a plan to solve the debt crisis at a summit on Friday.

The ratings agency's threat to downgrade euro zone countries en masse came hard on the heels of a Franco-German initiative, to be discussed on Friday, to enforce budget discipline across the 17-member zone through EU treaty changes.

The UK benchmark <.FTSE> looks set to shed 42 to 57 points, or as much as 1 percent, according to financial bookmakers, having risen 15.67 points, or 0.3 percent, to 5,567.96 on Monday.

* Nikkei falls 0.

UK stocks to watch on Tuesday are:

WOLSELEY

The building supplies group issues a trading update.

EASYJET

The budget airline issues traffic figures.

VICTREX

The manufacturer of high performance polymers issues full-year results.

NORTHGATE

The van hire company reports first-half results.

MONKS INVESTMENT TRUST

The company reports first-half results.

ELECTRA PRIVATE EQUITY

The company reports full-year results.