After falling 2.5% on Tuesday on concerns that a merger with US peers Reynolds and Lorillard might collapse, Imperial added 2.8% to Â£30.47.
Barclays added 2.7% to 249.2p, while a broker upgrade helped Lloyds Banking Group gain 1.4% to 79.4p.
After rising as high as 65 points in lunchtime trade, the FTSE 100 closed up 36.46 points at 6,809.5.
Kingfisher was the top faller among the blue chips, sinking 3.3% to 368p after announcing plans to close 60 B&Q stores on Tuesday.
In the FTSE 250, FirstGroup soared 6.8% to 97.15p after broker Panmure Gordon raised its rating on the transport group to "buy" from "hold".
Ocado fell almost 4.1% to 339.4p, making it the top faller on the 250. The stock is down 15% this year.
On the currency markets, the pound ended the day flat against the dollar at $1.4823, while against the euro, sterling dropped 0.23% to â‚¬1.377.
The euro was bolstered by further signs that momentum in the eurozone economy is improving.
The latest purchasing managers' index (PMI) for the eurozone's manufacturing sector rose to a 10-month high of 52.2 in March. A figure above 50 indicates expansion.
(Close): The London market ended the day up 0.5%, with Imperial Tobacco topping the leaders' board.